add json11 package (#33)

* add libyuv package

* update libyuv to upstream 1922

* add json11 package

json11/json11/__init__.py

@@ -0,0 +1,10 @@
+import os
+
+DIR = os.path.join(os.path.dirname(__file__), "install")
+LIB_DIR = os.path.join(DIR, "lib")
+INCLUDE_DIR = os.path.join(DIR, "include")
+
+
+def smoketest():
+  assert os.path.isfile(os.path.join(LIB_DIR, "libjson11.a")), "libjson11.a not found"
+  assert os.path.isfile(os.path.join(INCLUDE_DIR, "json11", "json11.hpp")), "json11/json11.hpp not found"