tree-wide: introduce mfree()

Pretty trivial helper which wraps free() but returns NULL, so we can
simplify this:
        free(foobar);
        foobar = NULL;
to this:
        foobar = mfree(foobar);

1 files changed, 1 insertions, 2 deletions

diff --git a/src/journal/coredumpctl.c b/src/journal/coredumpctl.c
index fc49b2e174..098f62af50 100644
--- a/src/journal/coredumpctl.c
+++ b/src/journal/coredumpctl.c
@@ -587,8 +587,7 @@ static int save_core(sd_journal *j, int fd, char **path, bool *unlink_temp) {
         if (filename && access(filename, R_OK) < 0) {
                 log_full(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
                          "File %s is not readable: %m", filename);
-                free(filename);
-                filename = NULL;
+                filename = mfree(filename);
         }
 
         if (filename && !endswith(filename, ".xz") && !endswith(filename, ".lz4")) {