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/ProgramFragment.java b/graphics/java/android/renderscript/ProgramFragment.java
index 5e04f0c..d06d768 100644
--- a/graphics/java/android/renderscript/ProgramFragment.java
+++ b/graphics/java/android/renderscript/ProgramFragment.java
@@ -106,16 +106,18 @@
             mPointSpriteEnable = false;
         }
 
-        public void setTexture(EnvMode env, Format fmt, int slot)
+        public Builder setTexture(EnvMode env, Format fmt, int slot)
             throws IllegalArgumentException {
             if((slot < 0) || (slot >= MAX_TEXTURE)) {
                 throw new IllegalArgumentException("MAX_TEXTURE exceeded.");
             }
             mSlots[slot] = new Slot(env, fmt);
+            return this;
         }
 
-        public void setPointSpriteTexCoordinateReplacement(boolean enable) {
+        public Builder setPointSpriteTexCoordinateReplacement(boolean enable) {
             mPointSpriteEnable = enable;
+            return this;
         }
 
         public ProgramFragment create() {