Building vanilla sbcl gives
cc -I../src/runtime -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -m32 -fno-omit-frame-pointer grovel-headers.c -ldl -lpthread -lzstd -o grovel-headers
So someone first had to remove "D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64" before breaking it with -D_GNU_SOURCE
Building vanilla sbcl gives
cc -I../src/runtime -D_LARGEFILE_SOURCE -D_LARGEFILE64_ SOURCE -D_FILE_ OFFSET_ BITS=64 -m32 -fno-omit- frame-pointer grovel-headers.c -ldl -lpthread -lzstd -o grovel-headers
So someone first had to remove "D_LARGEFILE_SOURCE -D_LARGEFILE64_ SOURCE -D_FILE_ OFFSET_ BITS=64" before breaking it with -D_GNU_SOURCE