Restart va_list in SkDebugf on win32.

src/ports/SkDebug_win.cpp

Index: src/ports/SkDebug_win.cpp
===================================================================
--- src/ports/SkDebug_win.cpp	(revision 8018)
+++ src/ports/SkDebug_win.cpp	(working copy)
@@ -19,10 +19,14 @@
 void SkDebugf(const char format[], ...) {
     char    buffer[kBufferSize + 1];
     va_list args;
+
     va_start(args, format);
-    vsnprintf(buffer, kBufferSize, format, args);
     vprintf(format, args);
     va_end(args);
 
+    va_start(args, format);
+    vsnprintf(buffer, kBufferSize, format, args);
+    va_end(args);
+
     OutputDebugStringA(buffer);
 }