CLEANUP: proxy: remove stop_time related dead code

Since eb77824 ("MEDIUM: proxy: remove the deprecated "grace" keyword"),
stop_time is never set, so the related code in manage_proxy() is not
relevant anymore.

Removing code that refers to p->stop_time, since it was probably
overlooked.
diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index 50c8488..cee87f5 100644
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -379,7 +379,6 @@
 	struct ist header_unique_id; 		/* unique-id header */
 	struct list format_unique_id;		/* unique-id format */
 	int to_log;				/* things to be logged (LW_*) */
-	int stop_time;                          /* date to stop listening, when stopping != 0 (int ticks) */
 	int nb_req_cap, nb_rsp_cap;		/* # of headers to be captured */
 	struct cap_hdr *req_cap;		/* chained list of request headers to be captured */
 	struct cap_hdr *rsp_cap;		/* chained list of response headers to be captured */
diff --git a/src/proxy.c b/src/proxy.c
index b44d537..1e4e36c 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -1988,20 +1988,6 @@
 	 * global resource here.
 	 */
 
-	/* first, let's check if we need to stop the proxy */
-	if (unlikely(stopping && !(p->flags & (PR_FL_DISABLED|PR_FL_STOPPED)))) {
-		int t;
-		t = tick_remain(now_ms, p->stop_time);
-		if (t == 0) {
-			stop_proxy(p);
-			/* try to free more memory */
-			pool_gc(NULL);
-		}
-		else {
-			next = tick_first(next, p->stop_time);
-		}
-	}
-
 	/* If the proxy holds a stick table, we need to purge all unused
 	 * entries. These are all the ones in the table with ref_cnt == 0
 	 * and all the ones in the pool used to allocate new entries. Any