Issue error on "void" typed variable, function parameter, or struct member.

tests_errors/void-1.ispc

@@ -0,0 +1,5 @@
+// "void" type variable illegal in declaration
+
+int func() {
+    void x;
+}

tests_errors/void-2.ispc

@@ -0,0 +1,5 @@
+// Parameter with type "void" illegal in function parameter list
+
+void func(void x, void y) {
+    return x+y;
+}

tests_errors/void-3.ispc

@@ -0,0 +1,5 @@
+// "void" type illegal for struct member
+
+struct Foo {
+    void x;
+};

tests_errors/void-4.ispc

@@ -0,0 +1,3 @@
+// "void" type global variable is illegal
+
+void x;

tests_errors/void-array-1.ispc

@@ -0,0 +1,5 @@
+// Arrays of "void" type are illegal
+
+float f_fu(uniform void aFOO[]) {
+    return 0;
+}

tests_errors/void-array-2.ispc

@@ -0,0 +1,4 @@
+// Arrays of "void" type are illegal
+
+uniform void aFOO[] = { NULL };
+

tests_errors/void-array-3.ispc

@@ -0,0 +1,7 @@
+// Arrays of "void" type are illegal
+
+struct Foo {
+    void aFOO[];
+};
+
+