[mutter] build: Fix distcheck

[Carlos Garnacho <carlosg src gnome org>]

commit 69f56578a319a5a7830982f4b73c189e6eb24b34
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Feb 18 12:26:04 2018 +0100

    build: Fix distcheck
    
    Missing protocol XML in wayland_protocols/EXTRA_DIST.
    
    https://gitlab.gnome.org/GNOME/mutter/issues/35
    
    Closes: #35

 src/Makefile.am | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/Makefile.am b/src/Makefile.am
index 3519afc11..15fb98c5e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -94,6 +94,7 @@ endif
 wayland_protocols =                            \
        wayland/protocol/gtk-shell.xml          \
        wayland/protocol/gtk-primary-selection.xml      \
+       wayland/protocol/gtk-text-input.xml     \
        $(NULL)
 
 libmutter_@LIBMUTTER_API_VERSION@_la_SOURCES = \