FIXED_PHOTO_VIEWER and DISABLE_PHOTO_VIEWER.
* mainproc.c (check_sig_and_print): Use --show-photos to show photos when
verifying a sig made by a key with a photo.
* keyserver.c (parse_keyserver_uri): Properly parse a URI with no :port
section and an empty file path, but with a terminating '/'.
(keyserver_work): Honor DISABLE_KEYSERVER_HELPERS.
* hkp.c (hkp_ask_import): Display keyserver URI as a URI, but only if
verbose.
* exec.c, g10.c: USE_EXEC_PATH -> FIXED_EXEC_PATH
use the original keyserver URI for cosmetics rather than trying to
recreate it when needed.
* mainproc.c (check_sig_and_print): Properly disregard expired uids.
Make sure that the first uid listed is a real uid and not an attribute
(attributes should only be listed in the "aka" section). When there are
no valid textual userids, try for an invalid textual userid before using
any attribute uid.
