fix [part of] #H103 - misleading prompt when choosing role,&c

fix [part of] #H103 - misleading prompt when choosing role,&c

     From a bug report, specifying role and race
along with invalid alignment for that role/race combination resulted in a
prompt of "pick the alignment of your chaotic human Valkyrie".  This fixes
that particular problem, but the role selection code is incomprehensible
and I don't have a lot of confidence about whether other combinations have
similar trouble.

     This also fixes an obvious typo in ok_align().  Unfortunately I can't
figure out what to do with the if-then-else block in root_plselection_prompt
which has identical code for its `then' and `else' halves (in the alignment
code that the new ok_align() test skips).