tree-wide: use coccinelle to patch a lot of code to use mfree()

This replaces this:

        free(p);
        p = NULL;

by this:

        p = mfree(p);

Change generated using coccinelle. Semantic patch is added to the
sources.

src/basic/lockfile-util.c

@@ -145,8 +145,7 @@ void release_lock_file(LockFile *f) {
                 if ((f->operation & ~LOCK_NB) == LOCK_EX)
                         unlink_noerrno(f->path);
 
-                free(f->path);
-                f->path = NULL;
+                f->path = mfree(f->path);
         }
 
         f->fd = safe_close(f->fd);