Make webkit-greeter optional

--- greeters/Makefile.am
+++ greeters/Makefile.am	2010-09-07 22:14:42.287187204 +0200
@@ -1,4 +1,7 @@
-libexec_PROGRAMS = ldm-gtk-greeter ldm-webkit-greeter
+libexec_PROGRAMS = ldm-gtk-greeter
+if WEBKIT
+  libexec_PROGRAMS += ldm-webkit-greeter
+endif
 
 LIBGREETER_LIB = $(top_builddir)/libldmgreeter/libldmgreeter.la
 LIBGREETER_CFLAGS = \
--- configure.ac
+++ configure.ac
@@ -9,10 +9,11 @@
 AC_PROG_LIBTOOL
 AM_MAINTAINER_MODE
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES(yes)])
+PKG_PROG_PKG_CONFIG
 
 GOBJECT_INTROSPECTION_CHECK(0.6.7)
 
-GNOME_COMPILE_WARNINGS(maximum)
+dnl GNOME_COMPILE_WARNINGS(maximum)
 
 dnl ###########################################################################
 dnl Dependencies
@@ -66,11 +67,16 @@
     dbus-glib-1
 ])
 
-PKG_CHECK_MODULES(LIGHTDM_WKGREETER, [
-    gtk+-2.0
-    webkit-1.0
-    dbus-glib-1
+AC_ARG_ENABLE([webkit], AC_HELP_STRING([--enable-webkit],[Build with webkit interface]))
+
+AS_IF([test "x$enable_webkit" != "xno"], [
+    PKG_CHECK_MODULES(LIGHTDM_WKGREETER, [
+       gtk+-2.0
+       webkit-1.0
+       dbus-glib-1
+    ])
 ])
+AM_CONDITIONAL([WEBKIT], [test x$webkit = xtrue])
 
 AC_PATH_PROG(GLIB_GENMARSHAL, glib-genmarshal)
 AC_PATH_PROG(DBUSBINDINGTOOL, dbus-binding-tool)
@@ -190,7 +196,7 @@
 dnl Documentation
 dnl ###########################################################################
 
-GNOME_DOC_INIT
+dnl GNOME_DOC_INIT
 GTK_DOC_CHECK
 
 dnl ###########################################################################
--- Makefile.am
+++ Makefile.am
@@ -1,3 +1,5 @@
+ACLOCAL_AMFLAGS = -I m4
+
 SUBDIRS = libldmgreeter data greeters po src themes doc
 
 DISTCHECK_CONFIGURE_FLAGS = --enable-introspection --enable-gtk-doc