gpg: Pass --homedir to gpg-agent.

* agent/gpg-agent.c (main): Make sure homedir is absolute.
* common/asshelp.c (lock_spawning): Create lock file with an absolute
name.
(start_new_gpg_agent): Use an absolute name for the socket and pass
option --homedir to the agent.
(start_new_dirmngr): Use an absolute name for the --homedir.
--

This patch makes gpg's --homedir option behave again like in older
versions.  This is done by starting a new agent for each different
home directory.  Note that this assumes --use-standard-socket is used
which is the default for 2.1.

agent/gpg-agent.c

@@ -885,6 +885,10 @@ main (int argc, char **argv )
   if (nogreeting )
     greeting = 0;
 
+  /* Turn the homedir into an absolute one. */
+  opt.homedir = make_absfilename (opt.homedir, NULL);
+
+
   if (greeting)
     {
       es_fprintf (es_stderr, "%s %s; %s\n",