Add back the meson build system to xserver.

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

xserver/exa/meson.build

@@ -0,0 +1,24 @@
+srcs_exa = [
+    'exa.c',
+    'exa_classic.c',
+    'exa_migration_classic.c',
+    'exa_driver.c',
+    'exa_mixed.c',
+    'exa_migration_mixed.c',
+    'exa_accel.c',
+    'exa_glyphs.c',
+    'exa_offscreen.c',
+    'exa_render.c',
+    'exa_unaccel.c',
+]
+
+libxserver_exa = static_library('libxserver_exa',
+    srcs_exa,
+    include_directories: inc,
+    dependencies: common_dep,
+    c_args: '-DHAVE_XORG_CONFIG_H'
+)
+
+if build_xorg
+    install_data('exa.h', install_dir: xorgsdkdir)
+endif