[libchamplain] Update gtk-doc.m4 to new version

[JiÅÃ Techet <jiritechet src gnome org>]

commit ed6c9799798538fa83a594afcef44c97c8ae4c1f
Author: JiÅÃ Techet <techet gmail com>
Date:   Sat Sep 17 00:22:39 2011 +0200

    Update gtk-doc.m4 to new version

 m4/gtk-doc.m4 |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/m4/gtk-doc.m4 b/m4/gtk-doc.m4
index 2cfa1e7..0ada151 100644
--- a/m4/gtk-doc.m4
+++ b/m4/gtk-doc.m4
@@ -6,6 +6,7 @@ dnl Usage:
 dnl   GTK_DOC_CHECK([minimum-gtk-doc-version])
 AC_DEFUN([GTK_DOC_CHECK],
 [
+  AC_REQUIRE([PKG_PROG_PKG_CONFIG])
   AC_BEFORE([AC_PROG_LIBTOOL],[$0])dnl setup libtool first
   AC_BEFORE([AM_PROG_LIBTOOL],[$0])dnl setup libtool first
 
@@ -33,6 +34,11 @@ AC_DEFUN([GTK_DOC_CHECK],
                         AC_MSG_ERROR([gtk-doc not installed and --enable-gtk-doc requested]))],
       [PKG_CHECK_EXISTS([gtk-doc >= $1],,
                         AC_MSG_ERROR([You need to have gtk-doc >= $1 installed to build $PACKAGE_NAME]))])
+    dnl don't check for glib if we build glib
+    if test "x$PACKAGE_NAME" != "xglib"; then
+      dnl don't fail if someone does not have glib
+      PKG_CHECK_MODULES(GTKDOC_DEPS, glib-2.0 >= 2.10.0 gobject-2.0  >= 2.10.0,,)
+    fi
   fi
 
   AC_MSG_CHECKING([whether to build gtk-doc documentation])