add linux support for examples and libs

native_client_sdk/src/examples/websocket/example.dsc

 {
-  'TOOLS': ['newlib', 'glibc', 'pnacl', 'win'],
+  'TOOLS': ['newlib', 'glibc', 'pnacl', 'win', 'linux'],
   'TARGETS': [
     {
       'NAME' : 'websocket',
       'TYPE' : 'main',
       'SOURCES' : ['websocket.cc'],
       'LIBS': ['ppapi_cpp', 'ppapi']
     }
   ],
   'DEST': 'examples',
   'NAME': 'websocket',
   'TITLE': 'Websocket',
   'DESC': """
 The Websocket example demonstrates how to use the Websocket API.  The
 user first connects to the test server: ws://html5rocks.websocket.org/echo by
 clicking on the 'Connect'' button.  Then hitting Send' will cause the app to
 send the message to the server and retrieve the reply.""",
   'INFO': 'Websockets'
 }