HLSL: Fix #1432: Globally initialize local static variables.

Test/hlsl.staticFuncInit.frag

@@ -0,0 +1,20 @@
+static float x = 1.0;
+
+float f1()
+{
+    static float x = 2.0;
+    x += 10.0;
+    return x;
+}
+
+float f2(float p)
+{
+    static float x = 7.0;
+    x += p;
+    return x;
+}
+
+float4 main() : SV_TARGET
+{
+    return x + f1() + f1() + f2(5.0) + f2(x);
+}