MINOR: config: Test validity of tune.maxaccept during the config parsing

Only -1 and positive integers from 0 to INT_MAX are accepted. An error is
triggered during the config parsing for any other values.

This patch may be backported to all supported versions.
diff --git a/src/cfgparse-global.c b/src/cfgparse-global.c
index bd8b68a..1633700 100644
--- a/src/cfgparse-global.c
+++ b/src/cfgparse-global.c
@@ -141,6 +141,8 @@
 		global.tune.maxpollevents = atol(args[1]);
 	}
 	else if (!strcmp(args[0], "tune.maxaccept")) {
+		long max;
+
 		if (alertif_too_many_args(1, file, linenum, args, &err_code))
 			goto out;
 		if (global.tune.maxaccept != 0) {
@@ -153,7 +155,13 @@
 			err_code |= ERR_ALERT | ERR_FATAL;
 			goto out;
 		}
-		global.tune.maxaccept = atol(args[1]);
+		max = atol(args[1]);
+		if (/*max < -1 || */max > INT_MAX) {
+			ha_alert("parsing [%s:%d] : '%s' expects -1 or an integer from 0 to INT_MAX.\n", file, linenum, args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		global.tune.maxaccept = max;
 	}
 	else if (!strcmp(args[0], "tune.chksize")) {
 		if (alertif_too_many_args(1, file, linenum, args, &err_code))