log-hander: Fix leak of rotate_filename in cleanup path

Running `obmc-console-server` under valgrind yields:

```
==259265== 34 bytes in 1 blocks are definitely lost in loss record 1 of 1
==259265==    at 0x48407B4: malloc (vg_replace_malloc.c:381)
==259265==    by 0x49BC427: __vasprintf_internal (vasprintf.c:71)
==259265==    by 0x498FBD5: asprintf (asprintf.c:31)
==259265==    by 0x10F2EF: log_init (log-handler.c:189)
==259265==    by 0x10EBEB: handlers_init (console-server.c:564)
==259265==    by 0x10EBEB: main (console-server.c:1000)
```

Free rotate_filename to avoid the leak.

Change-Id: Ib403d50d47b5d266bab415944cbae93582ecdb65
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

log-handler.c

diff --git a/log-handler.c b/log-handler.c
index 4109d8b..b77dd82 100644
--- a/log-handler.c
+++ b/log-handler.c
@@ -202,6 +202,7 @@
 	return &lh->handler;
 
 err_free:
+	free(lh->rotate_filename);
 	free(lh->log_filename);
 	free(lh);
 	return NULL;