Generate shaders to cover all possible cases.

With this change, all the vertex and fragment shaders used by the GL
renderer are now generated based on a program description supplied
by the caller. This allows the renderer to generate a large number
of shaders without having to write all the possible combinations by
hand. The generated shaders are stored in a program cache.

Change-Id: If54d286e77ae021c724d42090da476df12a18ebb
diff --git a/libs/hwui/shaders/drawLinearGradient.vert b/libs/hwui/shaders/drawLinearGradient.vert
index f5c669b..d2f857d 100644
--- a/libs/hwui/shaders/drawLinearGradient.vert
+++ b/libs/hwui/shaders/drawLinearGradient.vert
@@ -2,10 +2,10 @@
 
 attribute vec4 position;
 
+uniform mat4 transform;
 uniform float gradientLength;
 uniform vec2 gradient;
 uniform vec2 start;
-uniform mat4 transform;
 uniform mat4 screenSpace;
 
 varying float index;