package/gensio: add libglib2 optional dependency

libglib2 is an optional dependency which is enabled by default since
version 2.3.0 and
https://github.com/cminyard/gensio/commit/866924d69dabe8b8a981e19bd745d5c84e529881

Handle it properly to avoid the following build failure since bump to
version 2.5.2 in commit 5bb747f0b783a0d3f1712350ca3277263045b299:

sparc64-buildroot-linux-gnu-gcc: ERROR: unsafe header/library path used in cross-compilation: '-I/usr/include/glib-2.0'

Fixes:
 - http://autobuild.buildroot.org/results/3602c5cc2aff668211fd8e6eeab778b3fe287246

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gensio/gensio.mk

@@ -14,6 +14,13 @@ GENSIO_CONF_OPTS = \
 	--without-swig \
 	--without-python
 
+ifeq ($(BR2_PACKAGE_LIBGLIB2),y)
+GENSIO_DEPENDENCIES += host-pkgconf libglib2
+GENSIO_CONF_OPTS += --with-glib
+else
+GENSIO_CONF_OPTS += --without-glib
+endif
+
 ifeq ($(BR2_PACKAGE_OPENIPMI),y)
 GENSIO_DEPENDENCIES += openipmi
 GENSIO_CONF_OPTS += --with-openipmi