Use __printf__ in gcc function attributes to avoid clash with libc wrapper

define, and remove the last bits of the old workaround.

hw/xfree86/common/xf86.h

@@ -226,11 +226,6 @@ void xf86ProcessActionEvent(ActionEvent action, void *arg);
 
 /* xf86Helper.c */
 
-#ifdef printf
-#define printf_defined
-#undef printf
-#endif
-
 void xf86AddDriver(DriverPtr driver, pointer module, int flags);
 void xf86DeleteDriver(int drvIndex);
 ScrnInfoPtr xf86AllocateScreen(DriverPtr drv, int flags);

include/os.h

@@ -502,16 +502,11 @@ typedef enum {
 /* XXX Need to check which GCC versions have the format(printf) attribute. */
 #if defined(__GNUC__) && \
     ((__GNUC__ > 2) || ((__GNUC__ == 2) && (__GNUC_MINOR__ > 4)))
-#define _printf_attribute(a,b) __attribute((format(printf,a,b)))
+#define _printf_attribute(a,b) __attribute((format(__printf__,a,b)))
 #else
 #define _printf_attribute(a,b) /**/
 #endif
 
-#ifdef printf
-#define printf_defined
-#undef printf
-#endif
-
 extern const char *LogInit(const char *fname, const char *backup);
 extern void LogClose(void);
 extern Bool LogSetParameter(LogParameter param, int value);