Use va_list variable safely

src/ports/SkDebug_android.cpp

Index: src/ports/SkDebug_android.cpp
diff --git a/src/ports/SkDebug_android.cpp b/src/ports/SkDebug_android.cpp
index 70029fbb6db965169e10a41db994d9175fa72bc4..b41abd309110bba5a0600344828548d0a2d6e97b 100644
--- a/src/ports/SkDebug_android.cpp
+++ b/src/ports/SkDebug_android.cpp
@@ -22,15 +22,17 @@ extern "C" void AndroidSkDebugToStdOut(bool debugToStdOut) {
 }
 
 void SkDebugf(const char format[], ...) {
-    va_list args;
-    va_start(args, format);
-    __android_log_vprint(ANDROID_LOG_DEBUG, LOG_TAG, format, args);
+    va_list args1, args2;
+    va_start(args1, format);
+    va_copy(args2, args1);
+    __android_log_vprint(ANDROID_LOG_DEBUG, LOG_TAG, format, args1);
 
     // Print debug output to stdout as well.  This is useful for command
     // line applications (e.g. skia_launcher)
     if (gSkDebugToStdOut) {
-        vprintf(format, args);
+        vprintf(format, args2);
     }
 
-    va_end(args);
+    va_end(args1);
+    va_end(args2);
 }