package/openssh: fix build error on powerpc

Fixes the following error message introducted by OpenSSH v9.6p1.

  sshkey.c: In function 'sshkey_set_filename':
  sshkey.c:3705:1: sorry, unimplemented: '-fzero-call-used-regs' not supported on this target
   3705 | }

Fixes:
http://autobuild.buildroot.org/results/ec7/ec780aed5b1c4fdf9b91f6e7be99e8d4c42efa58

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/openssh/0001-better-detection-of-broken-fzero-call-used-regs.patch

@@ -0,0 +1,57 @@
+From 1036d77b34a5fa15e56f516b81b9928006848cbd Mon Sep 17 00:00:00 2001
+From: Damien Miller <djm@mindrot.org>
+Date: Fri, 22 Dec 2023 17:56:26 +1100
+Subject: [PATCH] better detection of broken -fzero-call-used-regs
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+gcc 13.2.0 on ppc64le refuses to compile some function, including
+cipher.c:compression_alg_list() with an error:
+
+> sorry, unimplemented: argument ‘used’ is not supportedcw
+> for ‘-fzero-call-used-regs’ on this target
+
+This extends the autoconf will-it-work test with a similarly-
+structured function that seems to catch this.
+
+Spotted/tested by Colin Watson; bz3645
+
+Upstream: https://github.com/openssh/openssh-portable/commit/1036d77b34a5fa15e56f516b81b9928006848cbd.patch
+Signed-off-by: Brandon Maier <brandon.maier@collins.com>
+---
+ m4/openssh.m4 | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/m4/openssh.m4 b/m4/openssh.m4
+index 5d4c56280fc..033df501c3d 100644
+--- a/m4/openssh.m4
++++ b/m4/openssh.m4
+@@ -20,18 +20,24 @@ char *f2(char *s, ...) {
+ 	va_end(args);
+ 	return strdup(ret);
+ }
++const char *f3(int s) {
++	return s ? "good" : "gooder";
++}
+ int main(int argc, char **argv) {
+-	(void)argv;
+ 	char b[256], *cp;
++	const char *s;
+ 	/* Some math to catch -ftrapv problems in the toolchain */
+ 	int i = 123 * argc, j = 456 + argc, k = 789 - argc;
+ 	float l = i * 2.1;
+ 	double m = l / 0.5;
+ 	long long int n = argc * 12345LL, o = 12345LL * (long long int)argc;
++	(void)argv;
+ 	f(1);
+-	snprintf(b, sizeof b, "%d %d %d %f %f %lld %lld\n", i,j,k,l,m,n,o);
++	s = f3(f(2));
++	snprintf(b, sizeof b, "%d %d %d %f %f %lld %lld %s\n", i,j,k,l,m,n,o,s);
+ 	if (write(1, b, 0) == -1) exit(0);
+-	cp = f2("%d %d %d %f %f %lld %lld\n", i,j,k,l,m,n,o);
++	cp = f2("%d %d %d %f %f %lld %lld %s\n", i,j,k,l,m,n,o,s);
++	if (write(1, cp, 0) == -1) exit(0);
+ 	free(cp);
+ 	/*
+ 	 * Test fallthrough behaviour.  clang 10's -Wimplicit-fallthrough does

package/openssh/openssh.mk

@@ -13,6 +13,9 @@ OPENSSH_SITE = http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable
 OPENSSH_LICENSE = BSD-3-Clause, BSD-2-Clause, Public Domain
 OPENSSH_LICENSE_FILES = LICENCE
 
+# 0001-better-detection-of-broken-fzero-call-used-regs.patch
+OPENSSH_AUTORECONF = YES
+
 OPENSSH_CONF_ENV = \
 	LD="$(TARGET_CC)" \
 	LDFLAGS="$(TARGET_CFLAGS)" \