Move test/libcxx/android/ to utils/libcxx/android/

This got refactored upstream.

Test: checkbuild and ./run_tests.py
Change-Id: I801869923cf7c51528de354f8a3da705f188ff43

utils/libcxx/android/build.py

@@ -0,0 +1,13 @@
+import os
+import subprocess
+
+
+def mm(path, android_build_top):
+    env = os.environ
+    env['ONE_SHOT_MAKEFILE'] = os.path.join(path, 'Android.mk')
+
+    cmd = [
+        'make', '-C', android_build_top, '-f', 'build/core/main.mk',
+        'MODULES-IN-' + path.replace('/', '-'), '-B'
+    ]
+    return not subprocess.Popen(cmd, stdout=None, stderr=None, env=env).wait()