libui: Enable -Weverything and -Werror

Enables -Weverything and -Werror, with just a few exceptions for
warnings we can't (or shouldn't need to) work around.

Change-Id: I470a267e9b1c373f2d5c960f005c3b0e02b2db63
diff --git a/include/ui/Fence.h b/include/ui/Fence.h
index 20466b6..b431bd5 100644
--- a/include/ui/Fence.h
+++ b/include/ui/Fence.h
@@ -65,7 +65,7 @@
     // before the fence signals then -ETIME is returned.  A timeout of
     // TIMEOUT_NEVER may be used to indicate that the call should wait
     // indefinitely for the fence to signal.
-    status_t wait(unsigned int timeout);
+    status_t wait(int timeout);
 
     // waitForever is a convenience function for waiting forever for a fence to
     // signal (just like wait(TIMEOUT_NEVER)), but issuing an error to the