[mutter] clutter: Install x11 related header files when using autotools again

[Jonas Ådahl <jadahl src gnome org>]

commit c03a401f4c6f4bd5e6d474b121b99161140a019a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Nov 7 12:02:35 2018 +0100

    clutter: Install x11 related header files when using autotools again
    
    clutter-x11.h and x11/clutter-x11-texture-pixmap.h were not installed
    any longer. Fix that.

 clutter/clutter/Makefile.am | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/clutter/clutter/Makefile.am b/clutter/clutter/Makefile.am
index 028f056e8..b97bd6693 100644
--- a/clutter/clutter/Makefile.am
+++ b/clutter/clutter/Makefile.am
@@ -438,6 +438,9 @@ backend_source_c_priv += $(x11_source_c_priv)
 # the list of files we want to introspect on X11
 x11_introspection = $(x11_source_c) $(x11_source_h)
 
+clutterx11_includedir = $(clutter_includedir)/x11
+clutterx11_include_HEADERS = $(x11_source_h)
+
 mutter-clutter-x11-@LIBMUTTER_API_VERSION@.pc: mutter-clutter-$(LIBMUTTER_API_VERSION).pc
        $(QUIET_GEN)cp -f $< $(@F)