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/libs/ui/UiConfig.cpp b/libs/ui/UiConfig.cpp
index 8b2130e..9e7ba8e 100644
--- a/libs/ui/UiConfig.cpp
+++ b/libs/ui/UiConfig.cpp
@@ -18,8 +18,11 @@
 
 namespace android {
 
+#ifdef FRAMEBUFFER_FORCE_FORMAT
+// We need the two-level macro to stringify the contents of a macro argument
 #define STRINGIFY(x) #x
 #define TOSTRING(x) STRINGIFY(x)
+#endif
 
 void appendUiConfigString(String8& configStr)
 {