Use #include "mymath.h" instead of declaring fabs() explicitly.

This should solve a weird problem on the Mac for Jack.

Objects/stringobject.c

@@ -33,6 +33,7 @@ PERFORMANCE OF THIS SOFTWARE.
 
 #include "Python.h"
 
+#include "mymath.h"
 #include <ctype.h>
 
 #ifdef COUNT_ALLOCS
@@ -627,8 +628,6 @@ getnextarg(args, arglen, p_argidx)
 #define F_ALT	(1<<3)
 #define F_ZERO	(1<<4)
 
-extern double fabs Py_PROTO((double));
-
 static int
 formatfloat(buf, flags, prec, type, v)
 	char *buf;