HBSD: Properly return status of public key validity check

Signed-off-by:	Shawn Webb <shawn.webb@hardenedbsd.org>
Reported-by:	Fabian Keil
github-issue:	#171
Sponsored-by:	G2, Inc

Author: lattera

usr.sbin/hbsd-update/hbsd-update

@@ -151,6 +151,7 @@ check_pubkey_validity() {
 		${caopt} ${capath} \
 		${tmpdir}/pubkey.pem \
 		> /dev/null 2>&1
+	res=${?}
 	return ${res}
 }