log: new object logging support

So that we can provide the specific object id in every log associated
to a given object.

test/mmrules.c

@@ -51,7 +51,8 @@ static GOptionEntry main_entries[] = {
 };
 
 void
-_mm_log (const char *loc,
+_mm_log (gpointer obj,
+         const char *loc,
          const char *func,
          guint32 level,
          const char *fmt,

test/mmsmspdu.c

@@ -164,7 +164,8 @@ show_part_info (MMSmsPart *part)
 }
 
 void
-_mm_log (const char *loc,
+_mm_log (gpointer obj,
+         const char *loc,
          const char *func,
          guint32     level,
          const char *fmt,

test/mmtty.c

@@ -84,7 +84,8 @@ signals_handler (int signum)
 }
 
 void
-_mm_log (const char *loc,
+_mm_log (gpointer obj,
+         const char *loc,
          const char *func,
          guint32 level,
          const char *fmt,