* main.h, g10.c (main), keygen.c (build_personal_digest_list): Put in a

default digest preference list consisting of SHA-1, followed by every
other installed digest except MD5.  Note this is the same as having no
digest preference at all except for SHA-1 being favored.

* options.h, g10.c (main), keygen.c (keygen_set_std_prefs), pkclist.c
(select_algo_from_prefs): Split --personal-preference-list into three:
--personal-{cipher|digest|compress}-preferences.  This allows a user to
set one without affecting another (i.e. setting only a digest pref doesn't
imply an empty cipher pref).

* exec.c (exec_read): This is a safer way of guessing the return value of
system().  Noted by Stefan Bellon.

g10/exec.c

@@ -485,7 +485,7 @@ int exec_read(struct exec_info *info)
 	}
 #else
       /* If we don't have the macros, do the best we can. */
-      info->progreturn/=256;
+      info->progreturn = (info->progreturn & 0xff00) >> 8;
 #endif
 
       /* 127 is the magic value returned from system() to indicate