gnulib: remove uneccessary func module

The gnulib 'func' modules provides portability to compilers which lack
the '__func__' symbol. We only care about GCC and CLang compilers so do
not need this compatibility code.
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

bootstrap.conf

@@ -48,7 +48,6 @@ ffs
 ffsl
 fnmatch
 fsync
-func
 getaddrinfo
 getcwd-lgpl
 gethostname