BUG/MINOR: mux-h1: Don't increment HTTP error counter for 408/500/501 errors

The HTTP error counter reflects the number of errors caused by
clients. Thus, In the H1 mux, it should only be increment on parsing errors.

This fix is specific for 2.4. No backport needed.
diff --git a/src/mux_h1.c b/src/mux_h1.c
index 01343c3..8f96cdf 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -2394,7 +2394,6 @@
 	int ret = 1;
 
 	session_inc_http_req_ctr(sess);
-	session_inc_http_err_ctr(sess);
 	proxy_inc_fe_req_ctr(sess->listener, sess->fe);
 	_HA_ATOMIC_ADD(&sess->fe->fe_counters.p.http.rsp[5], 1);
 	_HA_ATOMIC_ADD(&sess->fe->fe_counters.internal_errors, 1);
@@ -2447,7 +2446,6 @@
 		goto end;
 
 	session_inc_http_req_ctr(sess);
-	session_inc_http_err_ctr(sess);
 	proxy_inc_fe_req_ctr(sess->listener, sess->fe);
 	_HA_ATOMIC_ADD(&sess->fe->fe_counters.p.http.rsp[4], 1);
 	_HA_ATOMIC_ADD(&sess->fe->fe_counters.failed_req, 1);
@@ -2474,7 +2472,6 @@
 		goto end;
 
 	session_inc_http_req_ctr(sess);
-	session_inc_http_err_ctr(sess);
 	proxy_inc_fe_req_ctr(sess->listener, sess->fe);
 	_HA_ATOMIC_ADD(&sess->fe->fe_counters.p.http.rsp[4], 1);
 	_HA_ATOMIC_ADD(&sess->fe->fe_counters.failed_req, 1);