do not include system libs in shared libs

emcc

@@ -1411,7 +1411,7 @@ try:
   extra_files_to_link = []
 
   if not LEAVE_INPUTS_RAW and \
-     not shared.Settings.BUILD_AS_SHARED_LIB == 2 and \
+     not shared.Settings.BUILD_AS_SHARED_LIB and \
      not shared.Settings.SIDE_MODULE: # shared libraries/side modules link no C libraries, need them in parent
 
     # Check if we need to include some libraries that we compile. (We implement libc ourselves in js, but