Remove some FIXMEs left in from initial work.

LIFE_EXEC is already dealt with, and I forgot to take out the comment
reminding me to do it, ahem.

The LIFE_PARENT mentioned in the same comment was an idea I had but
couldn't think of a way to make it work: if you have a terminal-only
shell session in which you want to eval $(ssh-agent), then it's
annoying and fragile to have to remember to kill the agent when you
log out, so you'd like it to automatically tie its lifetime to that of
the shell from which you invoked it. Unfortunately, I don't know of
any way to do that without race conditions. (E.g. if only pageant
didn't fork, then it could poll its own ppid until it became 1 - but
the child process would find it was 1 already.)

unix/uxpgnt.c

@@ -389,15 +389,6 @@ int main(int argc, char **argv)
             termination_pid = pid;
         }
     }
-    /*
-     * FIXME: and if life == LIFE_EXEC, then we use our own pid, but
-     * don't print_env - instead, fork, stuff it in the real
-     * environment, and exec our child.
-     *
-     * FIXME: and hang on, perhaps LIFE_PARENT won't work after all,
-     * because after we fork, of course, our ppid _isn't_ an indicator
-     * of whether the target process has gone away.
-     */
 
     now = GETTICKCOUNT();