main/openvpn-auth-ldap: disable on riscv64

temp disable due to missing object-c gcc support

main/openvpn-auth-ldap/APKBUILD

@@ -4,7 +4,7 @@ pkgver=2.0.4
 pkgrel=3
 pkgdesc="LDAP authentication and authorization plugin for OpenVPN 2.x"
 url="https://github.com/threerings/openvpn-auth-ldap/"
-arch="all"
+arch="all !riscv64"
 license="BSD-3-Clause"
 depends="openvpn"
 makedepends="automake autoconf re2c openldap-dev openvpn-dev gcc-objc"