build-aux: only forbid gethostname in C files
build-aux: only forbid gethostname in C files

This function is fine to use in other languages

Reviewed-by: Cole Robinson <7cd45ff6ad1fb7cf556a02797d774247851499f8@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,zippy2/libvirt,zippy2/libvirt,libvirt/libvirt,libvirt/libvirt,libvirt/libvirt,jfehlig/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,olafhering/libvirt,zippy2/libvirt,olafhering/libvirt