Minor refactor, break out new fn svc_find_by_str()

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/svc.h

@@ -210,6 +210,7 @@ int	    svc_del	           (svc_t *svc);
 void	    svc_validate	   (svc_t *svc);
 
 svc_t	   *svc_find	           (char *name, char *id);
+svc_t	   *svc_find_by_str        (const char *str);
 svc_t	   *svc_find_by_pid        (pid_t pid);
 svc_t	   *svc_find_by_cond	   (const char *cond);
 svc_t	   *svc_find_by_jobid      (int job, char *id);