Add an SK_PRINTF_LIKE macro, which declares a function to have printf-like
semantics, allowing gcc and clang to check the format string against the
arguments.  Enable its use on SkString (printf, appendf, and prependf).  Also
define an SK_SIZE_T_SPECIFIER macro so there's a cross-platform way of
printing a size_t.

Review URL:  http://codereview.appspot.com/6375043/



git-svn-id: http://skia.googlecode.com/svn/trunk@4485 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/Debugger/SkDebugDumper.cpp b/experimental/Debugger/SkDebugDumper.cpp
index 64ac2eb..69b1896 100644
--- a/experimental/Debugger/SkDebugDumper.cpp
+++ b/experimental/Debugger/SkDebugDumper.cpp
@@ -28,7 +28,7 @@
 
 static void appendPtr(SkString* str, const void* ptr, const char name[]) {
     if (ptr) {
-        str->appendf("$s: %p\t", name, ptr);
+        str->appendf("%s: %p\t", name, ptr);
     }
 }