Comment 0 for bug 1834143

libfdt 1.5.7-3 as currently in C/D/E defines some functions that it then fails to export.
Due to that programs build against its headers might fail later on.

For example qemu:
cc -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fPIE -DPIE -m64 -mcx16 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -std=gnu99 -g -O2 -fdebug-prefix-map=/<<BUILDDIR>>/qemu-4.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -Wexpansion-to-defined -Wendif-labels -Wno-shift-negative-value -Wno-missing-include-dirs -Wempty-body -Wnested-externs -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration -Wold-style-definition -Wtype-limits -fstack-protector-strong -I/usr/include/p11-kit-1 -I/usr/include/libpng16 -o config-temp/qemu-conf.exe config-temp/qemu-conf.c -Wl,-z,relro -Wl,-z,now -pie -m64 -g -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,--as-needed -lfdt
/usr/bin/ld: /tmp/cck74tTE.o: in function `main':
./b/qemu/config-temp/qemu-conf.c:3: undefined reference to `fdt_check_full'

A fix to that is already upstream [1] and should be an easy backport that also "only" adds symbols - so it should be rather SRU safe.

[1]: https://github.com/dgibson/dtc/commit/eac2ad495b29f15d78daa2a7226653f36515cd7a