This hasn't been needed in quite some time.
https://bugzilla.gnome.org/show_bug.cgi?id=692052
# Sets GLIB_GENMARSHAL and GLIB_MKENUMS
AM_PATH_GLIB_2_0()
-G_IR_SCANNER=`$PKG_CONFIG --variable=g_ir_scanner gobject-introspection-1.0`
-AC_SUBST(G_IR_SCANNER)
-G_IR_COMPILER=`$PKG_CONFIG --variable=g_ir_compiler gobject-introspection-1.0`
-AC_SUBST(G_IR_COMPILER)
-G_IR_GENERATE=`$PKG_CONFIG --variable=g_ir_generate gobject-introspection-1.0`
-AC_SUBST(G_IR_GENERATE)
-GIRDIR=`$PKG_CONFIG --variable=girdir gobject-introspection-1.0`
-AC_SUBST(GIRDIR)
-TYPELIBDIR="$($PKG_CONFIG --variable=typelibdir gobject-introspection-1.0)"
-AC_SUBST(TYPELIBDIR)
GTK_DOC_CHECK([1.15], [--flavour no-tmpl])