Add back the meson build system to xserver.

Not having those file only create noise when merging upstream releases.

xserver/xfixes/meson.build

@@ -0,0 +1,14 @@
+srcs_xfixes = [
+    'cursor.c',
+    'disconnect.c',
+    'region.c',
+    'saveset.c',
+    'select.c',
+    'xfixes.c',
+]
+
+libxserver_xfixes = static_library('libxserver_xfixes',
+    srcs_xfixes,
+    include_directories: inc,
+    dependencies: common_dep,
+)