Add tests for function pointers.

tests/funcptr-uniform-9.ispc

@@ -0,0 +1,28 @@
+
+export uniform int width() { return programCount; }
+
+typedef float (*FuncType)(float, float);
+
+float foo(float a, float b) {
+    return a+b;
+}
+
+static float bar(float a, float b) {
+    if (a < b)
+        return a;
+    else
+        return b;
+}
+
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    uniform FuncType func[] = { foo, bar };
+    float a = aFOO[programIndex]; 
+    float b = aFOO[0]-1; // == 0
+    RET[programIndex] = ((a == 1) ? bar : foo)(a, b);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = programIndex+1;
+    RET[0] = 0;
+}