Test pseudo-namespaces in C

In C you can create pseudo-namespaces by abusing structs of function
pointers, making function calls look like `module.func(x)` instead of
`func(x)`.

A lot of people online spout that this creates overhead, but this should
show that clang>=15.0.7 will still inline such function calls. GCC 11.3.1
is unable  to inline the function, but will still call the function
directly.

main.c

@@ -0,0 +1,22 @@
+
+#include <stdio.h>
+
+#include "module.h"
+
+int main()
+{
+	int x = 4;
+
+#ifdef NAMESPACES
+#pragma message "namespaces enabled"
+	x = module.succ(x);
+	x = module.succ(x);
+#else
+	x = succ(x);
+	x = succ(x);
+#endif
+
+	printf("%d\n", x);
+
+	return 0;
+}