Making Program*.Builder classes' setters return 'this'

This is for better correspondence with the Builder pattern.
See also: Effective Java, 2nd edition.

Change-Id: Iecccd42be49dea2ed8e4b8cc38ce96379cf3c11c
diff --git a/graphics/java/android/renderscript/ProgramStore.java b/graphics/java/android/renderscript/ProgramStore.java
index f558117..a92cbb6 100644
--- a/graphics/java/android/renderscript/ProgramStore.java
+++ b/graphics/java/android/renderscript/ProgramStore.java
@@ -114,28 +114,33 @@
 
         }
 
-        public void setDepthFunc(DepthFunc func) {
+        public Builder setDepthFunc(DepthFunc func) {
             mDepthFunc = func;
+            return this;
         }
 
-        public void setDepthMask(boolean enable) {
+        public Builder setDepthMask(boolean enable) {
             mDepthMask = enable;
+            return this;
         }
 
-        public void setColorMask(boolean r, boolean g, boolean b, boolean a) {
+        public Builder setColorMask(boolean r, boolean g, boolean b, boolean a) {
             mColorMaskR = r;
             mColorMaskG = g;
             mColorMaskB = b;
             mColorMaskA = a;
+            return this;
         }
 
-        public void setBlendFunc(BlendSrcFunc src, BlendDstFunc dst) {
+        public Builder setBlendFunc(BlendSrcFunc src, BlendDstFunc dst) {
             mBlendSrc = src;
             mBlendDst = dst;
+            return this;
         }
 
-        public void setDitherEnable(boolean enable) {
+        public Builder setDitherEnable(boolean enable) {
             mDither = enable;
+            return this;
         }
 
         static synchronized ProgramStore internalCreate(RenderScript rs, Builder b) {