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/bitmap.c

@@ -145,8 +145,7 @@ bool bitmap_isclear(Bitmap *b) {
 void bitmap_clear(Bitmap *b) {
         assert(b);
 
-        free(b->bitmaps);
-        b->bitmaps = NULL;
+        b->bitmaps = mfree(b->bitmaps);
         b->n_bitmaps = 0;
         b->bitmaps_allocated = 0;
 }

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);

src/basic/strv.c

@@ -271,8 +271,7 @@ char **strv_split_newlines(const char *s) {
                 return l;
 
         if (isempty(l[n-1])) {
-                free(l[n-1]);
-                l[n-1] = NULL;
+                l[n - 1] = mfree(l[n - 1]);
         }
 
         return l;