Fix misc-macro-parentheses warnings in opengl.

Bug: 28705665
Change-Id: I761d310f0dff182c288cdbb5371272f4833aa282
diff --git a/opengl/tests/hwc/hwcRects.cpp b/opengl/tests/hwc/hwcRects.cpp
index 56c1a2a..ba242ab 100644
--- a/opengl/tests/hwc/hwcRects.cpp
+++ b/opengl/tests/hwc/hwcRects.cpp
@@ -137,7 +137,7 @@
 #define CMD_START_FRAMEWORK  "start 2>&1"
 
 // Macros
-#define NUMA(a) (sizeof(a) / sizeof(a [0])) // Num elements in an array
+#define NUMA(a) (sizeof(a) / sizeof((a)[0])) // Num elements in an array
 
 // Local types
 class Rectangle {