core: New global flags "inst-type".
* src/gpgme.c (gpgme_set_global_flag): Add flag "inst-type". * src/w32-util.c (_gpgme_set_get_inst_type): New. (INST_TYPE_GPG4WIN_DIR): New. (INST_TYPE_GPGDESK_DIR): New. (_gpgme_get_gpgconf_path): Implement this flag. Replace fixed strings by the macros. * src/posix-util.c (_gpgme_set_get_inst_type): New dummy.
This is intended for use by Kleopatra to reliable find the expected
GnuPG installation.