Upstream nettle-sys builds fine, but the package from debian doesn't. If I don't apply the debian patches, the build also works fine.

This is the diff between a build with and without the debian patches:

without patches:
    Updating crates.io index
   Compiling libc v0.2.147
   Compiling glob v0.3.1
   Compiling proc-macro2 v1.0.66
   Compiling memchr v2.5.0
   Compiling cfg-if v1.0.0
   Compiling unicode-ident v1.0.11
   Compiling minimal-lexical v0.2.1
   Compiling rustix v0.38.7
   Compiling regex-syntax v0.7.4
   Compiling syn v1.0.109
   Compiling linux-raw-sys v0.4.5
   Compiling bindgen v0.63.0
   Compiling bitflags v2.3.3
   Compiling peeking_take_while v0.1.2
   Compiling shlex v1.1.0
   Compiling fastrand v2.0.0
   Compiling libloading v0.7.4
   Compiling lazy_static v1.4.0
   Compiling rustc-hash v1.1.0
   Compiling bitflags v1.3.2
   Compiling lazycell v1.3.0
   Compiling pkg-config v0.3.27
   Compiling clang-sys v1.6.1
   Compiling nom v7.1.3
   Compiling quote v1.0.32
   Compiling cc v1.0.82
   Compiling tempfile v3.7.1
   Compiling cexpr v0.6.0
   Compiling regex-automata v0.3.6
   Compiling regex v1.9.3
   Compiling nettle-sys v2.2.0 (/home/ubuntu/git/packages/rust-nettle-sys/rust-nettle-sys)
    Finished release [optimized] target(s) in 11.00s


With patches:
    Updating crates.io index                                                                                                                                   
   Compiling libc v0.2.147                                                                                                                                     
   Compiling glob v0.3.1                                                                                                                                       
   Compiling memchr v2.5.0                                                                                                                                     
   Compiling proc-macro2 v1.0.66                                                                                                                               
   Compiling cfg-if v1.0.0                                                                                                                                     
   Compiling regex-syntax v0.7.4                                                                                                                               
   Compiling unicode-ident v1.0.11                                                                                                                             
   Compiling rustix v0.38.7                                                                                                                                    
   Compiling minimal-lexical v0.2.1                                                                                                                            
   Compiling bitflags v2.3.3                                                                                                                                   
   Compiling linux-raw-sys v0.4.5                                                                                                                              
   Compiling bindgen v0.60.1                                                                                                                                   
   Compiling peeking_take_while v0.1.2                                                                                                                         
   Compiling rustc-hash v1.1.0                                                                                                                                 
   Compiling bitflags v1.3.2                                                                                                                                   
   Compiling lazy_static v1.4.0                                                                                                                                
   Compiling libloading v0.7.4                                                                                                                                 
   Compiling fastrand v2.0.0                                                                                                                                   
   Compiling lazycell v1.3.0                                                                                                                                   
   Compiling shlex v1.1.0                                                                                                                                      
   Compiling pkg-config v0.3.27                                                                                                                                
   Compiling clang-sys v1.6.1                                                                                                                                  
   Compiling nom v7.1.3                                                                                                                                        
   Compiling quote v1.0.32                                                                                                                                     
   Compiling cc v1.0.82                                                                                                                                        
   Compiling regex-automata v0.3.6                                                                                                                             
   Compiling tempfile v3.7.1                                                                                                                                   
   Compiling cexpr v0.6.0                                                                                                                                      
   Compiling regex v1.9.3
   Compiling nettle-sys v2.2.0 (/home/ubuntu/git/packages/rust-nettle-sys/rust-nettle-sys)
error: failed to run custom build command for `nettle-sys v2.2.0 (/home/ubuntu/git/packages/rust-nettle-sys/rust-nettle-sys)`

The differences between failed and succeeded builds are:

-   Compiling bindgen v0.60.1
+   Compiling bindgen v0.63.0

and

+   Compiling syn v1.0.109