* agent/genkey.c (do_check_passphrase_pattern): Use the gpgrt API.
* common/asshelp.c (start_new_service): Ditto.
* common/exechelp.h: Remove gnupg_process_spawn API.
* common/exechelp-posix.c: Remove gnupg_process_spawn implementation.
* common/exechelp-w32.c: Likewise.
* common/exectool.c (gnupg_exec_tool_stream): Use the gpgrt API.
* common/t-exechelp.c (test_pipe_stream): Remove.
* dirmngr/ldap-wrapper.c (destroy_wrapper, ldap_reaper_thread): Use
the gpgrt API.
(ldap_wrapper_connection_cleanup, ldap_wrapper): Ditto.
* dirmngr/ldap.c, g10/call-keyboxd.c: No need to include exechelp.h.
* g10/photoid.c (run_with_pipe, show_photo): Use the gpgrt API.
* g13/be-encfs.c (run_umount_helper, run_encfs_tool): Ditto.
* g13/g13.c, g13/mount.c, g13/runner.c: No need to include exechelp.h.
* scd/apdu.c: No need to include exechelp.h.
* scd/app.c (report_change): Use the gpgrt API.
* sm/export.c, sm/import.c: No need to include exechelp.h.
* tests/gpgscm/ffi.c (proc_object_finalize, proc_wrap)
(do_process_spawn_io, do_process_spawn_fd, do_process_wait): Use the
gpgrt API.
* tools/gpg-auth.c: No need to include exechelp.h.
* tools/gpg-card.c (cmd_gpg): Use the gpgrt API.
* tools/gpg-connect-agent.c: No need to include exechelp.h.
* tools/gpg-mail-tube.c (mail_tube_encrypt, prepare_for_appimage)
(start_gpg_encrypt): Use the gpgrt API.
* tools/gpgconf-comp.c (gpg_agent_runtime_change)
(scdaemon_runtime_change, tpm2daemon_runtime_change)
(dirmngr_runtime_change, keyboxd_runtime_change)
(gc_component_launch, gc_component_check_options)
(retrieve_options_from_program): Ditto.
* tools/gpgconf.c (show_versions_via_dirmngr): Ditto.
* tools/gpgtar-create.c (gpgtar_create): Ditto.
* tools/gpgtar-extract.c (gpgtar_extract): Ditto.
* tools/gpgtar-list.c (gpgtar_list): Ditto.