oksh-noxz [fork] Portable OpenBSD ksh, based on the Public Domain Korn Shell (pdksh).
	git clone https://noxz.tech/git/oksh-noxz.git
	oksh-noxz

commit: 6c54d46febf147dea97cd4c4e86438ced1136401
parent: 2d633adbebdd68bcd99a50c2e555ee7c2d2744d6
author: Brian Callahan <bcallah@openbsd.org>
date:   Thu, 23 Jul 2020 10:21:23 -0400

For loop initial declarations is a better C99 check for older gcc
versions.

diff --git a/configure b/configure
@@ -103,7 +103,7 @@ EOF
 c99check() {
   cat << EOF > conftest.c
 #include <stdio.h>
-int main(void){long long l;printf("%s",__func__);return 0;}
+int main(void){long long l;for (int i=0;i<1;i++)printf("%s",__func__);return 0;}
 EOF
   $cc $cflags $ldflags -o conftest conftest.c > /dev/null 2>&1
   if [ $? -eq 0 ] ; then