meson: Add Xvfb and Xephyr-glamor testing.

The Xvfb tests are passing and Xephyr-glamor is failing for me, but it
fails identically on autotools.  It's disabled on Travis for now
because the >10 minutes of silence during testing times out the entire
build.

v2: Fix the disable on travis.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Adam Jackson <ajax@redhat.com>

test/scripts/xephyr-glamor-piglit.sh

@@ -1,3 +1,10 @@
+#!/bin/sh
+
+# this times out on Travis, because the tests take too long.
+if test "x$TRAVIS_BUILD_DIR" != "x"; then
+    exit 77
+fi
+
 # Start a Xephyr server using glamor.  Since the test environment is
 # headless, we start an Xvfb first to host the Xephyr.
 export PIGLIT_RESULTS_DIR=$XSERVER_BUILDDIR/test/piglit-results/xephyr-glamor

test/scripts/xvfb-piglit.sh

@@ -1,3 +1,10 @@
+#!/bin/sh
+
+# this times out on Travis, because the tests take too long.
+if test "x$TRAVIS_BUILD_DIR" != "x"; then
+    exit 77
+fi
+
 export SERVER_COMMAND="$XSERVER_BUILDDIR/hw/vfb/Xvfb \
         -noreset \
         -screen scrn 1280x1024x24"