changing vec4 to vec2 for perf reasons.

Change-Id: Ic885a6dc697af4fd82e184158772863673f041bd
diff --git a/graphics/java/android/renderscript/ProgramFragment.java b/graphics/java/android/renderscript/ProgramFragment.java
index c1d6428..8858b74 100644
--- a/graphics/java/android/renderscript/ProgramFragment.java
+++ b/graphics/java/android/renderscript/ProgramFragment.java
@@ -104,7 +104,7 @@
         private void buildShaderString() {
             mShader  = "//rs_shader_internal\n";
             mShader += "varying lowp vec4 varColor;\n";
-            mShader += "varying vec4 varTex0;\n";
+            mShader += "varying vec2 varTex0;\n";
 
             mShader += "void main() {\n";
             if (mVaryingColorEnable) {