build: drop the ldexp gnulib module

The ldexp gnulib module adds "-lm" to the $LIBS variable if-and-only-if
the ldexp() function require linking to libm. There is no harm in
linking to libm even if it isn't required for ldexp(), so simply drop
the gnulib module.

Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

bootstrap.conf

@@ -54,7 +54,6 @@ intprops
 ioctl
 isatty
 largefile
-ldexp
 listen
 localeconv
 maintainer-makefile

src/util/Makefile.inc.am

@@ -279,6 +279,7 @@ libvirt_util_la_CFLAGS = \
 	$(ACL_CFLAGS) \
 	$(NULL)
 libvirt_util_la_LIBADD = \
+	-lm \
 	$(CAPNG_LIBS) \
 	$(YAJL_LIBS) \
 	$(LIBNL_LIBS) \