MINOR: proxy: Introduce proxy flags to replace disabled bitfield

This change is required to support TCP/HTTP rules in defaults sections. The
'disabled' bitfield in the proxy structure, used to know if a proxy is
disabled or stopped, is replaced a generic bitfield named 'flags'.

PR_DISABLED and PR_STOPPED flags are renamed to PR_FL_DISABLED and
PR_FL_STOPPED respectively. In addition, everywhere there is a test to know
if a proxy is disabled or stopped, there is now a bitwise AND operation on
PR_FL_DISABLED and/or PR_FL_STOPPED flags.
diff --git a/src/stick_table.c b/src/stick_table.c
index 4936677..ae22b83 100644
--- a/src/stick_table.c
+++ b/src/stick_table.c
@@ -654,7 +654,7 @@
 			t->exp_task->process = process_table_expire;
 			t->exp_task->context = (void *)t;
 		}
-		if (t->peers.p && t->peers.p->peers_fe && !t->peers.p->peers_fe->disabled) {
+		if (t->peers.p && t->peers.p->peers_fe && !(t->peers.p->peers_fe->flags & (PR_FL_DISABLED|PR_FL_STOPPED))) {
 			peers_retval = peers_register_table(t->peers.p, t);
 		}