gpg: Warn about (but don't fail) on scdaemon options in gpg.conf.

* g10/gpg.c: Add config options that should belong in scdaemon.conf
* g10/main.h, g10/misc.c (obsolete_scdaemon_option): New.

--

In gpg2, the following options are only relevant for scdaemon:

 reader-port
 ctapi-driver
 pcsc-driver
 disable-ccid

but in gpg1, they are options for gpg itself.

Some users of gpg1 might have these options in their
~/.gnupg/gpg.conf, which causes gpg2 to fail hard if it reads that
config file.

gpg2 should not fail hard, though giving a warning (and suggesting a
move to scdaemon.conf) seems OK.

This patch does *not* reintroduce any documentation for these options
in gpg.texi, even to indicate that they are "dummy" options, since
scdaemon.texi contains the appropriate documentation.

Debian-bug-id: 762844

Program names factored out from obsolete_scdaemon_option to make
reuse without new translations easier. -wk

This is a backport of commit 371c2b14b0
with parts of 20c6da50d4 but without those
which would change existing translated strings. -wk

g10/misc.c

@@ -851,6 +851,20 @@ obsolete_option (const char *configname, unsigned int configlineno,
 }
 
 
+void
+obsolete_scdaemon_option (const char *configname, unsigned int configlineno,
+                          const char *name)
+{
+  if (configname)
+    log_info (_("%s:%u: \"%s%s\" is obsolete in this file"
+                " - it only has effect in %s\n"),
+              configname, configlineno, name, "--", "scdaemon.conf");
+  else
+    log_info (_("WARNING: \"%s%s\" is an obsolete option"
+                " - it has no effect except on %s\n"), "--", name, "scdaemon");
+}
+
+
 /*
  * Wrapper around gcry_cipher_map_name to provide a fallback using the
  * "Sn" syntax as used by the preference strings.