fix memory corruption when retriving GL_MAX_VIEWPORT_DIMS

Change-Id: I2e0b1eac6dbc6a4ecbbaf31013aa02cf2369fce2
diff --git a/services/surfaceflinger/DisplayHardware/DisplayHardware.h b/services/surfaceflinger/DisplayHardware/DisplayHardware.h
index ee7a2af..cdf89fd 100644
--- a/services/surfaceflinger/DisplayHardware/DisplayHardware.h
+++ b/services/surfaceflinger/DisplayHardware/DisplayHardware.h
@@ -108,7 +108,7 @@
     PixelFormat     mFormat;
     uint32_t        mFlags;
     mutable uint32_t mPageFlipCount;
-    GLint           mMaxViewportDims;
+    GLint           mMaxViewportDims[2];
     GLint           mMaxTextureSize;
     
     HWComposer*     mHwc;