Fix build with older glib
diff --git a/configure.ac b/configure.ac
index ad2d2be..e5147ca 100644
--- a/configure.ac
+++ b/configure.ac
@@ -39,7 +39,7 @@
 
 dnl ==========================================================================
 
-PKG_CHECK_MODULES(GLIB, glib-2.0, have_glib=true, have_glib=false)
+PKG_CHECK_MODULES(GLIB, glib-2.0 >= 2.16, have_glib=true, have_glib=false)
 if $have_glib; then
 	AC_DEFINE(HAVE_GLIB, 1, [Have glib2 library])
 fi