Add a caps bit to enable/disable the new manual mip-mapper

src/gpu/gl/GrGLCaps.h

Index: src/gpu/gl/GrGLCaps.h
diff --git a/src/gpu/gl/GrGLCaps.h b/src/gpu/gl/GrGLCaps.h
index 1602a0f63d113935b2484de59a8778b9a4f9146f..58bf98c2d0b700570128cab2e0bf4db105678f83 100644
--- a/src/gpu/gl/GrGLCaps.h
+++ b/src/gpu/gl/GrGLCaps.h
@@ -333,6 +333,8 @@ public:
 
     bool mipMapLevelAndLodControlSupport() const { return fMipMapLevelAndLodControlSupport; }
 
+    bool doManualMipmapping() const { return fDoManualMipmapping; }
+
     /**
      * Returns a string containing the caps info.
      */
@@ -410,6 +412,7 @@ private:
     bool fTextureSwizzleSupport : 1;
     bool fMipMapLevelAndLodControlSupport : 1;
     bool fRGBAToBGRAReadbackConversionsAreSlow : 1;
+    bool fDoManualMipmapping : 1;
 
     BlitFramebufferSupport fBlitFramebufferSupport;