Check that coverage FPs are compatible with alpha as coverage

Change-Id: Ic3b6a02248d571e82f6729827c199d358fb75114
Reviewed-on: https://skia-review.googlesource.com/8508
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/include/gpu/GrTypesPriv.h b/include/gpu/GrTypesPriv.h
index 5b925bb..e7bb1ad 100644
--- a/include/gpu/GrTypesPriv.h
+++ b/include/gpu/GrTypesPriv.h
@@ -541,7 +541,7 @@
 #ifdef SK_DEBUG
 // Takes a pointer to a GrCaps, and will suppress prints if required
 #define GrCapsDebugf(caps, ...)         \
-    if (!caps->suppressPrints()) {      \
+    if (!(caps)->suppressPrints()) {    \
         SkDebugf(__VA_ARGS__);          \
     }
 #else