src: replace copy of printf mappings with an include

Closes #14648

lib/curlx.h

@@ -31,10 +31,8 @@
  * be.
  */
 
-#include <curl/mprintf.h>
+/* map standard printf functions to curl implementations */
-/* this is still a public header file that provides the curl_mprintf()
+#include "curl_printf.h"
-   functions while they still are offered publicly. They will be made library-
-   private one day */
 
 #include "strcase.h"
 /* "strcase.h" provides the strcasecompare protos */
@@ -77,25 +75,4 @@
 
 */
 
-/* We define all "standard" printf() functions to use the curlx_* version
-   instead. It makes the source code transparent and easier to
-   understand/patch. Undefine them first. */
-# undef printf
-# undef fprintf
-# undef msnprintf
-# undef vprintf
-# undef vfprintf
-# undef mvsnprintf
-# undef aprintf
-# undef vaprintf
-
-# define printf curl_mprintf
-# define fprintf curl_mfprintf
-# define msnprintf curl_msnprintf
-# define vprintf curl_mvprintf
-# define vfprintf curl_mvfprintf
-# define mvsnprintf curl_mvsnprintf
-# define aprintf curl_maprintf
-# define vaprintf curl_mvaprintf
-
 #endif /* HEADER_CURL_CURLX_H */