Cross-compilation of 'ltrace' fails with "error: libelf.h or gelf.h not found in your system" despite it being in /usr/local/include

Question

So I have an x86_64 arch and I need to compile for aarch64 (arm). I have libelf.h and gelf.h in /usr/local/include, which should be automatically included by gcc. I also tried exporting CPPFLAGS=-I/usr/local/include/libelf or using the with-libelf parameter of ltrace's configure file but I always get the same error in the title.

Any ideas? I've done similar cross-compilation before with strace successfully so I'm really struggling to understand what's wrong here.

Thanks in advance