Remove include of stdlib.h from SkTypes.h.

Unfortunately, immintrin.h (which is also included by SkTypes)
includes xmmintrin.h which includes mm_malloc.h which includes
stdlib.h for malloc even though, from the implementation, it is
difficult to see why.

Fortunately, arm_neon.h does not seem to be involved in such
shenanigans, so building for Android will keep things sane.

TBR=reed@google.com
Doesn't change Skia API, just moves an include.

Review URL: https://codereview.chromium.org/1313203003
diff --git a/samplecode/SamplePath.cpp b/samplecode/SamplePath.cpp
index 313abca..c09ff20 100644
--- a/samplecode/SamplePath.cpp
+++ b/samplecode/SamplePath.cpp
@@ -26,6 +26,8 @@
 
 #include "SkGeometry.h"
 
+#include <stdlib.h>
+
 // http://code.google.com/p/skia/issues/detail?id=32
 static void test_cubic() {
     SkPoint src[4] = {