Add support for broadcast(), rotate(), and shuffle() stdlib routines

tests/shuffle-2.ispc

@@ -0,0 +1,13 @@
+
+export uniform int width() { return programCount; }
+
+export void f_fu(uniform float RET[], uniform float aFOO[], uniform float b) {
+    float a = aFOO[programIndex]; 
+    int reverse = programCount - 1 - programIndex + (int)b - 5;
+    float shuf = shuffle(a, reverse);
+    RET[programIndex] = shuf;
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = programCount - programIndex;
+}