Fix alpha blending and improve fragment shaders performance.

Change-Id: Ib74f6941d25ca6f6a41708e541174eaa7e8d9bc2
diff --git a/libs/hwui/Program.cpp b/libs/hwui/Program.cpp
index 2acddfc..819e736 100644
--- a/libs/hwui/Program.cpp
+++ b/libs/hwui/Program.cpp
@@ -126,7 +126,7 @@
 
 void DrawColorProgram::getAttribsAndUniforms() {
     position = addAttrib("position");
-    color = addAttrib("color");
+    color = addUniform("color");
     projection = addUniform("projection");
     modelView = addUniform("modelView");
     transform = addUniform("transform");