common: Support locating components in the build tree.

* common/homedir.c (gnupg_build_directory): New variable.
(gnupg_module_name_called): Likewise.
(gnupg_set_builddir): New function.
(gnupg_set_builddir_from_env): Likewise.
(gnupg_module_name): Support locating components in the build tree.
* common/util.h (gnupg_set_builddir): New prototype.
* tests/openpgp/defs.scm (tools): Drop 'gpg and 'gpg-agent.
(tool): Rename to 'tool-hardcoded.
(gpg-conf): New function, with accessors for the results.
(gpg-components): New variable.
(tool): New function.
* tools/gpgconf.c (enum cmd_and_opt_values): New key.
(opts): New option '--build-prefix'.
(main): Handle new option.
--

This change makes sure that the components from the build tree are
used, and not some older installed version in PATH.  It also lets us
make GPGME use components from the build tree, making it possible to
execute GPGME's test suite with them.

Signed-off-by: Justus Winter <justus@g10code.com>

common/util.h

@@ -263,6 +263,7 @@ char *_gnupg_socketdir_internal (int skip_checks, unsigned *r_info);
 #define GNUPG_MODULE_NAME_GPGV          12
 const char *gnupg_module_name (int which);
 void gnupg_module_name_flush_some (void);
+void gnupg_set_builddir (const char *newdir);