[core] Prefer the endian.h header file from glibc if available
[core] Prefer the endian.h header file from glibc if available

On the Debian kfreebsd port, both endian.h and sys/endian.h are
available. After discussing with the kfreebsd port maintainer and since
this is userspace related, we should prefer the one from the glibc

See: #2066

ethouris/srt,Haivision/srt,Haivision/srt,ethouris/srt,Haivision/srt,Cinegy/srt,ethouris/srt,Haivision/srt,Cinegy/srt,Cinegy/srt,ethouris/srt,Cinegy/srt