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/bench/nanobench.cpp b/bench/nanobench.cpp
index 2720b6f..550a35f 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -41,6 +41,8 @@
 #include "SkSurface.h"
 #include "SkTaskGroup.h"
 
+#include <stdlib.h>
+
 #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
     #include "nanobenchAndroid.h"
 #endif