[libnotify] build: Use ${PKG_CONFIG} instead of pkg-config

[Marc-Antoine Perennou <marcop src gnome org>]

commit 6b03c47e04e556691445590c15d594aaff5a1066
Author: Quentin Glidic <sardemff7+git sardemff7 net>
Date:   Thu Nov 19 10:02:50 2015 +0100

    build: Use ${PKG_CONFIG} instead of pkg-config
    
    Some use cases (e.g. cross-compiling) require a prefixed pkg-config
    
    https://bugzilla.gnome.org/show_bug.cgi?id=758322
    
    Signed-off-by: Quentin Glidic <sardemff7+git sardemff7 net>

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 632e80d..b9764bc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -103,7 +103,7 @@ if test x$enable_tests = xyes ; then
 fi
 AM_CONDITIONAL(TESTS_ENABLED, test x$enable_tests = xyes)
 
-GLIB_GENMARSHAL=`pkg-config --variable=glib_genmarshal glib-2.0`
+GLIB_GENMARSHAL=`${PKG_CONFIG} --variable=glib_genmarshal glib-2.0`
 AC_SUBST(GLIB_GENMARSHAL)
 
 GOBJECT_INTROSPECTION_CHECK([0.9.12])