Sema: add missing validateRuntimeValue calls

Resolves: #13791

test/cases/compile_errors/for_comptime_array_pointer.zig

@@ -0,0 +1,12 @@
+export fn foo() void {
+    comptime var elems: [3]u32 = undefined;
+    for (&elems) |*elem| {
+        _ = elem;
+    }
+}
+
+// error
+//
+// :3:10: error: runtime value contains reference to comptime var
+// :3:10: note: comptime var pointers are not available at runtime
+// :2:34: note: 'runtime_value' points to comptime var declared here