gnupg: Enable SSH support for gpg-agent

This enables the ssh agent compatability of gpg-agent.

gnupg/.gnupg/gpg-agent.conf

@@ -1,3 +1,4 @@
 default-cache-ttl 14400
 max-cache-ttl 14400
 pinentry-program /usr/bin/pinentry-gnome3
+enable-ssh-support

shell/.profile

@@ -30,3 +30,10 @@ fi
 
 export VISUAL=vim
 export EDITOR="$VISUAL"
+
+export GPG_TTY=$(tty)
+
+unset SSH_AGENT_PID
+if [ "${gnupg_SSH_AUTH_SOCK_by:-0}" -ne $$ ]; then
+export SSH_AUTH_SOCK="$(gpgconf --list-dirs agent-ssh-socket)"
+fi