CLEANUP: atomic/tree-wide: replace single increments/decrements with inc/dec

This patch replaces roughly all occurrences of an HA_ATOMIC_ADD(&foo, 1)
or HA_ATOMIC_SUB(&foo, 1) with the equivalent HA_ATOMIC_INC(&foo) and
HA_ATOMIC_DEC(&foo) respectively. These are 507 changes over 45 files.
diff --git a/src/mux_h1.c b/src/mux_h1.c
index d3f3411..5b23a29 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -2409,10 +2409,10 @@
 
 	session_inc_http_req_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);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.p.http.rsp[5]);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.internal_errors);
 	if (sess->listener && sess->listener->counters)
-		_HA_ATOMIC_ADD(&sess->listener->counters->internal_errors, 1);
+		_HA_ATOMIC_INC(&sess->listener->counters->internal_errors);
 
 	h1c->errcode = 500;
 	ret = h1_send_error(h1c);
@@ -2434,10 +2434,10 @@
 	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);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.p.http.rsp[4]);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.failed_req);
 	if (sess->listener && sess->listener->counters)
-		_HA_ATOMIC_ADD(&sess->listener->counters->failed_req, 1);
+		_HA_ATOMIC_INC(&sess->listener->counters->failed_req);
 
 	h1c->errcode = 400;
 	ret = h1_send_error(h1c);
@@ -2461,10 +2461,10 @@
 
 	session_inc_http_req_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);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.p.http.rsp[4]);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.failed_req);
 	if (sess->listener && sess->listener->counters)
-		_HA_ATOMIC_ADD(&sess->listener->counters->failed_req, 1);
+		_HA_ATOMIC_INC(&sess->listener->counters->failed_req);
 
 	h1c->errcode = 501;
 	ret = h1_send_error(h1c);
@@ -2487,10 +2487,10 @@
 
 	session_inc_http_req_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);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.p.http.rsp[4]);
+	_HA_ATOMIC_INC(&sess->fe->fe_counters.failed_req);
 	if (sess->listener && sess->listener->counters)
-		_HA_ATOMIC_ADD(&sess->listener->counters->failed_req, 1);
+		_HA_ATOMIC_INC(&sess->listener->counters->failed_req);
 
 	h1c->errcode = 408;
 	ret = h1_send_error(h1c);