msg: bump up log level of --log-file

This now logs -v -v by default, instead of -v.

DOCS/man/options.rst

@@ -412,9 +412,9 @@ Program Behavior
 
 ``--log-file=<path>``
     Opens the given path for writing, and print log messages to it. Existing
-    files will be truncated. The log level is at least ``-v``, but can be
-    raised via ``--msg-level`` (the option cannot lower it below the forced
-    minimum log level).
+    files will be truncated. The log level is at least ``-v -v``, but
+    can be raised via ``--msg-level`` (the option cannot lower it below the
+    forced minimum log level).
 
 ``--config-dir=<path>``
     Force a different configuration directory. If this is set, the given

common/msg.c

@@ -120,7 +120,7 @@ static void update_loglevel(struct mp_log *log)
     for (int n = 0; n < log->root->num_buffers; n++)
         log->level = MPMAX(log->level, log->root->buffers[n]->level);
     if (log->root->log_file)
-        log->level = MPMAX(log->level, MSGL_V);
+        log->level = MPMAX(log->level, MSGL_DEBUG);
     if (log->root->stats_file)
         log->level = MPMAX(log->level, MSGL_STATS);
     atomic_store(&log->reload_counter, atomic_load(&log->root->reload_counter));
@@ -285,7 +285,7 @@ static void write_log_file(struct mp_log *log, int lev, char *text)
 {
     struct mp_log_root *root = log->root;
 
-    if (!root->log_file || lev > MPMAX(MSGL_V, log->terminal_level))
+    if (!root->log_file || lev > MPMAX(MSGL_DEBUG, log->terminal_level))
         return;
 
     fprintf(root->log_file, "[%8.3f][%c][%s] %s",