Don't leak memory if profile option is given twice

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/init.c b/init.c
index 1c37ab9..a0ec914 100644
--- a/init.c
+++ b/init.c
@@ -1828,6 +1828,8 @@
 			break;
 			}
 		case 'p':
+			if (exec_profile)
+				free(exec_profile);
 			exec_profile = strdup(optarg);
 			break;
 		case FIO_GETOPT_JOB: {