Don't use setresgid or setgid in ssh-agent

Fixes it for Android Pie, see #2714

packages/openssh/build.sh

@@ -47,7 +47,7 @@ termux_step_pre_configure() {
     ## prefixed path to program 'passwd'
     export PATH_PASSWD_PROG="${TERMUX_PREFIX}/bin/passwd"
 
-	CPPFLAGS+=" -DHAVE_ATTRIBUTE__SENTINEL__=1"
+	CPPFLAGS+=" -DHAVE_ATTRIBUTE__SENTINEL__=1 -DBROKEN_SETRESGID"
 	LD=$CC # Needed to link the binaries
 	LDFLAGS+=" -llog" # liblog for android logging in syslog hack
 }

packages/openssh/ssh-agent.c.patch

@@ -0,0 +1,15 @@
+diff -ruN a/ssh-agent.c b/ssh-agent.c
+--- a/ssh-agent.c	2018-08-08 13:44:30.076228968 +0200
++++ b/ssh-agent.c	2018-08-08 13:46:37.282997806 +0200
+@@ -1064,9 +1064,11 @@
+ 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
+ 	sanitise_stdfd();
+ 
++#ifndef __ANDROID__
+ 	/* drop */
+ 	setegid(getgid());
+ 	setgid(getgid());
++#endif
+ 
+ 	platform_disable_tracing(0);	/* strict=no */
+