CLEANUP: checks: remove 16 bytes of holes in struct check

These ones were easily recovered by swapping two members.
diff --git a/include/types/checks.h b/include/types/checks.h
index ac3e7b6..b1fe7f3 100644
--- a/include/types/checks.h
+++ b/include/types/checks.h
@@ -158,12 +158,12 @@
 struct check {
 	struct xprt_ops *xprt;			/* transport layer operations for health checks */
 	struct conn_stream *cs;			/* conn_stream state for health checks */
-	unsigned short port;			/* the port to use for the health checks */
 	struct buffer *bi, *bo;			/* input and output buffers to send/recv check */
 	struct task *task;			/* the task associated to the health check processing, NULL if disabled */
 	struct timeval start;			/* last health check start time */
 	long duration;				/* time in ms took to finish last health check */
 	short status, code;			/* check result, check code */
+	unsigned short port;			/* the port to use for the health checks */
 	char desc[HCHK_DESC_LEN];		/* health check description */
 	int use_ssl;				/* use SSL for health checks */
 	int send_proxy;				/* send a PROXY protocol header with checks */
@@ -177,8 +177,8 @@
 						 * rise to rise+fall-1 = good */
 	int rise, fall;				/* time in iterations */
 	int type;				/* Check type, one of PR_O2_*_CHK */
-	char *send_string;			/* optionally send a string when connecting to the agent */
 	int send_string_len;			/* length of agent command string */
+	char *send_string;			/* optionally send a string when connecting to the agent */
 	struct server *server;			/* back-pointer to server */
 	char **argv;				/* the arguments to use if running a process-based check */
 	char **envp;				/* the environment to use if running a process-based check */