[CLEANUP] use distinct bits per load-balancing algorithm type

It's useful to be able to check against an LB algorithm type by
testing just one bit.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index b407b07..07caa72 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -2531,7 +2531,7 @@
 				Warning("parsing %s : monitor-uri will be ignored for %s '%s'.\n",
 					file, proxy_type_str(curproxy), curproxy->id);
 			}
-			if (curproxy->lbprm.algo & BE_LB_ALGO_L7) {
+			if (curproxy->lbprm.algo & BE_LB_PROP_L7) {
 				curproxy->lbprm.algo &= ~BE_LB_ALGO;
 				curproxy->lbprm.algo |= BE_LB_ALGO_RR;