changing vec4 to vec2 for perf reasons.

Change-Id: Ic885a6dc697af4fd82e184158772863673f041bd
diff --git a/rsFont.cpp b/rsFont.cpp
index b9de7e1..a951005 100644
--- a/rsFont.cpp
+++ b/rsFont.cpp
@@ -497,7 +497,7 @@
 
 void FontState::initRenderState()
 {
-    String8 shaderString("varying vec4 varTex0;\n");
+    String8 shaderString("varying vec2 varTex0;\n");
     shaderString.append("void main() {\n");
     shaderString.append("  lowp vec4 col = UNI_Color;\n");
     shaderString.append("  col.a = texture2D(UNI_Tex0, varTex0.xy).a;\n");