Some fixes in function names and more tests was added.

tests/paddus_vi8.ispc

@@ -2,10 +2,10 @@
 export uniform int width() { return programCount; }
 
 export void f_f(uniform float RET[], uniform float aFOO[]) {
-    varying unsigned int8 a = 255, b = 255; // max unsigned int8
+    varying unsigned int8 a = 255, b = aFOO[programIndex]; // max unsigned int8
     RET[programIndex] = saturating_add(a, b);
 }
 
 export void result(uniform float RET[]) {
-    RET[programIndex] = 255;
+    RET[programIndex] = (varying unsigned int8) 255;
 }