mprintf.h: remove #ifdef CURLDEBUG

... and as a consequence, introduce curl_printf.h with that re-define
magic instead and make all libcurl code use that instead.

lib/curl_printf.h

@@ -0,0 +1,40 @@
+#ifndef HEADER_CURL_PRINTF_H
+#define HEADER_CURL_PRINTF_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+/*
+ * This header should be included by ALL code in libcurl that uses any
+ * *rintf() functions.
+ */
+
+#define _MPRINTF_REPLACE /* use our functions only */
+#include <curl/mprintf.h>
+
+/* We define away the sprintf functions unconditonally since we don't want
+   internal code to be using them, intentionally or by mistake!*/
+# undef sprintf
+# undef vsprintf
+# define sprintf sprintf_was_used
+# define vsprintf vsprintf_was_used
+
+#endif /* HEADER_CURL_PRINTF_H */