conditional compilation confusion and failure

I want to compile different files with a common *.c file. Like I want to compile A.c common.c xor B.c common.c but I can't figure out how to achieve that.

Can you please tell me how do I make common.c use different headers without using my text editor to change the headers list every time I want to compile

So let's say I have 3 files: A.c, B.c and common.c.

A.h and B.h define an enum enum {Mon, Tues, Wed...} in different ways. And that enum is used in common.c. So I can't just do in common.c:

#include "A.h"
#include "B.h"

What I thought of doing is to use preprocessor directives:

In common.h

#define A 1
#define B 2

In A.c

#define COMPILE_HEADER A

And in common.c

#if COMPILE_HEADER == A 
#include A.h 
#end

This doesn't work, ofcourse, because the compiler didnt visit the A.c file to find #define COMPILE_HEADER A

So can you please tell me how do I make common.c use different headers without using my text editor to change the headers list every time I want to compile?