Compiler: move checking function-scope-only builtins to AstGen

test/cases/compile_errors/function-only_builtins_outside_function.zig

@@ -0,0 +1,69 @@
+comptime {
+    @setAlignStack(1);
+}
+
+comptime {
+    @setCold(true);
+}
+
+comptime {
+    @src();
+}
+
+comptime {
+    @returnAddress();
+}
+
+comptime {
+    @frameAddress();
+}
+
+comptime {
+    @breakpoint();
+}
+
+comptime {
+    @cVaArg(1, 2);
+}
+
+comptime {
+    @cVaCopy(1);
+}
+
+comptime {
+    @cVaEnd(1);
+}
+
+comptime {
+    @cVaStart();
+}
+
+comptime {
+    @workItemId(42);
+}
+
+comptime {
+    @workGroupSize(42);
+}
+
+comptime {
+    @workGroupId(42);
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :2:5: error: '@setAlignStack' outside function scope
+// :6:5: error: '@setCold' outside function scope
+// :10:5: error: '@src' outside function scope
+// :14:5: error: '@returnAddress' outside function scope
+// :18:5: error: '@frameAddress' outside function scope
+// :22:5: error: '@breakpoint' outside function scope
+// :26:5: error: '@cVaArg' outside function scope
+// :30:5: error: '@cVaCopy' outside function scope
+// :34:5: error: '@cVaEnd' outside function scope
+// :38:5: error: '@cVaStart' outside function scope
+// :42:5: error: '@workItemId' outside function scope
+// :46:5: error: '@workGroupSize' outside function scope
+// :50:5: error: '@workGroupId' outside function scope