util/log: Rename logfilename to global_filename

Rename to emphasize this is the file-scope global variable.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220417183019.755276-33-richard.henderson@linaro.org>
diff --git a/util/log.c b/util/log.c
index 491a8f9..b3f79de 100644
--- a/util/log.c
+++ b/util/log.c
@@ -34,7 +34,7 @@
     FILE *fd;
 } QemuLogFile;
 
-static char *logfilename;
+static char *global_filename;
 static QemuMutex qemu_logfile_mutex;
 static QemuLogFile *qemu_logfile;
 int qemu_loglevel;
@@ -151,8 +151,8 @@
             }
         }
 
-        g_free(logfilename);
-        logfilename = newname;
+        g_free(global_filename);
+        global_filename = newname;
         filename = newname;
 
         if (logfile) {
@@ -161,7 +161,7 @@
             logfile = NULL;
         }
     } else {
-        filename = logfilename;
+        filename = global_filename;
     }
 
 #ifdef CONFIG_TRACE_LOG
@@ -173,9 +173,8 @@
      * In all cases we only log if qemu_loglevel is set.
      * Also:
      *   If not daemonized we will always log either to stderr
-     *     or to a file (if there is a logfilename).
-     *   If we are daemonized,
-     *     we will only log if there is a logfilename.
+     *     or to a file (if there is a filename).
+     *   If we are daemonized, we will only log if there is a filename.
      */
     need_to_open_file = log_flags && (!is_daemonized() || filename);