BUG/MINOR: config: clear proxy->table.peers.p for disabled proxies

If a table in a disabled proxy references a peers section, the peers
name is not resolved to a pointer to a table, but since it belongs to
a union, it can later be dereferenced. Right now it seems it cannot
happen, but it definitely will after the pending changes.

It doesn't cost anything to backport this into 1.5, it will make gdb
sessions less head-scratching.
(cherry picked from commit 02df7740fbb5bf55113d9082a237158e26751eea)
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 750c5ac..8e489a9 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -6108,6 +6108,8 @@
 		if (curproxy->state == PR_STSTOPPED) {
 			/* ensure we don't keep listeners uselessly bound */
 			stop_proxy(curproxy);
+			free((void *)curproxy->table.peers.name);
+			curproxy->table.peers.p = NULL;
 			continue;
 		}