Fix usage of SK_BUILD_* defines.
Since we just 'define' them, but not attribute anything to them, like
'1' for example, cpp expands it to nothing and that breaks the "#if"
clauses.
To fix that, uses "#if defined(...)" which will correctly check if your
macro name was defined or not.
BUG=skia:2850
TEST=make most
R=robertphillips@google.com
Review URL: https://codereview.chromium.org/628763005
diff --git a/tools/skpdiff/skpdiff_util.h b/tools/skpdiff/skpdiff_util.h
index 8750bf6..f626ac9 100644
--- a/tools/skpdiff/skpdiff_util.h
+++ b/tools/skpdiff/skpdiff_util.h
@@ -12,7 +12,7 @@
#include "SkTArray.h"
#if SK_SUPPORT_OPENCL
-#if SK_BUILD_FOR_MAC
+#if defined(SK_BUILD_FOR_MAC)
# include <OpenCL/cl.h>
#else
# include <CL/cl.h>