BUG/MEDIUM: config: propagate frontend to backend process binding again.

This basically reverts 3507d5d ("MEDIUM: proxy: only adjust the backend's
bind-process when already set"). It was needed during the transition to
the new process binding method but is causing trouble now because frontend
to backend binding is not properly propagated.

This fix should be backported to 1.5.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 2519e84..a9d7662 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -6260,9 +6260,8 @@
 				/* we force the backend to be present on at least all of
 				 * the frontend's processes.
 				 */
-				if (target->bind_proc)
-					target->bind_proc = curproxy->bind_proc ?
-						(target->bind_proc | curproxy->bind_proc) : 0;
+				target->bind_proc = curproxy->bind_proc ?
+					(target->bind_proc | curproxy->bind_proc) : 0;
 
 				/* Emit a warning if this proxy also has some servers */
 				if (curproxy->srv) {
@@ -6298,9 +6297,8 @@
 					/* we force the backend to be present on at least all of
 					 * the frontend's processes.
 					 */
-					if (target->bind_proc)
-						target->bind_proc = curproxy->bind_proc ?
-							(target->bind_proc | curproxy->bind_proc) : 0;
+					target->bind_proc = curproxy->bind_proc ?
+						(target->bind_proc | curproxy->bind_proc) : 0;
 				}
 			}
 		}
@@ -6352,9 +6350,8 @@
 				/* we force the backend to be present on at least all of
 				 * the frontend's processes.
 				 */
-				if (target->bind_proc)
-					target->bind_proc = curproxy->bind_proc ?
-						(target->bind_proc | curproxy->bind_proc) : 0;
+				target->bind_proc = curproxy->bind_proc ?
+					(target->bind_proc | curproxy->bind_proc) : 0;
 			}
 		}