hwc/copybit: Add Color layer support in MDP Copybit composition.

1. Color layer has a destination rectangle, RGBA color and plane
   alpha. There is no gralloc buffer. Layer flag HWC_COLOR_FILL
   denotes color layer. MDP BLIT happens via MDP_SOLID_FILL mode.
2. There is no color member in HWC layer, so RGBA color value is
   passed via "tranform" member from framework to HAL.
3. Update HWC query to enable framework to query for Color layer
   support in HAL, at run-time.

Change-Id: I2c698007c1689779fe86d549093bb5285432dc5f
diff --git a/libcopybit/copybit.h b/libcopybit/copybit.h
index 13d78b5..dbb89f0 100644
--- a/libcopybit/copybit.h
+++ b/libcopybit/copybit.h
@@ -242,6 +242,21 @@
                    struct copybit_rect_t const *src_rect,
                    struct copybit_region_t const *region);
 
+    /**
+     * Fill the rect on dst with RGBA color
+     *
+     * @param dev from open
+     * @param dst is destination image
+     * @param rect is destination rectangle
+     * @param color is RGBA color to fill
+     *
+     * @return 0 if successful
+     */
+    int (*fill_color)(struct copybit_device_t *dev,
+                      struct copybit_image_t const *dst,
+                      struct copybit_rect_t const *rect,
+                      uint32_t color);
+
   /**
     * Execute the completion of the copybit draw operation.
     *