MemoryTracking: fix logging of free() calls done where Curl_safefree is called

Just internal stuff...

Curl_safefree is now a macro defined in memdebug.h instead of a function
prototyped in url.h and implemented in url.c, so inclusion of url.h is no
longer required in order to simply use Curl_safefree.

Provide definition of macro WHILE_FALSE in setup_once.h in order to allow
other macros such as DEBUGF and DEBUGASSERT, and code using it, to compile
without 'conditional expression is constant' warnings.

The WHILE_FALSE stuff fixes 150+ MSVC compiler warnings.

lib/mprintf.c

@@ -103,7 +103,7 @@ static const char upper_digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
       done++; \
     else \
      return done; /* return immediately on failure */ \
-  } while(0)
+  } WHILE_FALSE
 
 /* Data type to read from the arglist */
 typedef enum  {