app-crypt/chntpw: force -std=gnu90

Just a workaround for build errors for now. In the long run, I think
I'd better look at whether how useful exactly (if at all) chntpw is
against modern Windows versions, warrants all the changes required
to make the code C99-compliant.

Nb. It's gnu90 rather than c90 because of the use of // for comments.

Closes: https://bugs.gentoo.org/919172
Signed-off-by: Marek Szuba <marecki@gentoo.org>

app-crypt/chntpw/chntpw-140201-r1.ebuild

@@ -1,9 +1,9 @@
-# Copyright 1999-2022 Gentoo Authors
+# Copyright 1999-2024 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
 
-inherit toolchain-funcs
+inherit flag-o-matic toolchain-funcs
 
 DESCRIPTION="Offline Windows NT Password & Registry Editor"
 HOMEPAGE="https://pogostick.net/~pnh/ntpasswd/"
@@ -34,6 +34,9 @@ src_prepare() {
 	default
 	sed -i -e '/-o/s:$(CC):$(CC) $(LDFLAGS):' Makefile || die
 
+	# MANY changes would be required for this code to be c99-compliant
+	append-flags -std=gnu90
+
 	if ! use static ; then
 		sed -i -e "/^all:/s/ \(chntpw\|reged\).static//g" Makefile || die
 	fi