Do not generate forwarding header for ewk headers
Unreviewed build fix on EFL port after r171356.

Implement a dummy platformMediaCacheDirectory() to avoid undefined reference error.

* UIProcess/efl/WebContextEfl.cpp:
(WebKit::WebContext::platformMediaCacheDirectory):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@171373 268f45cc-cd09-0410-ab3c-d52691b4dbfc