Update run_tests and examples makefile for scalar target.

Fixed a number of tests that didn't handle the programCount == 1
case correctly.

tests/atomics-10.ispc

@@ -13,5 +13,5 @@ export void f_f(uniform float RET[], uniform float aFOO[]) {
 }
 
 export void result(uniform float RET[]) {
-    RET[programIndex] = 2;
+    RET[programIndex] = programCount == 1 ? 1 : 2;
 }