libcbor needs libm

[bsiegert]

loaders.c includes math.h and calls ldexp, which is part of libm on many Unix-like systems.

On NetBSD/evbarm, linking the library fails because of an undefined reference to the ldexp symbol. Manually adding -lm to CMAKE_EXE_LINKER_FLAGS fixes the problem. However, libcbor should probably explicitly link in libm on Unix.

[bsiegert]

Thank you!

[PJK]

Thanks for reporting!