branch-2.4.2 ports from master

[Joel E. Denny]

I cherry picked the following from master to branch-2.4.2 except that I 
extracted the location.cc change from a commit that didn't apply on 
branch-2.4.2.

2008-11-07  Akim Demaille  <address@hidden>

        Fix --help.
        * src/getargs.c (usage): Fix help string for -W.

2008-11-07  Akim Demaille  <address@hidden>

        Handle more general types of option arguments.
        * build-aux/cross-options.pl: The argument ends at the first
        space, not the first non-symbol character.
        Use @var for each word appearing the argument description.

2009-04-04  Joel E. Denny  <address@hidden>

        Remove spurious initial empty lines.
        * data/location.cc: End the @output lines with an @.

2008-11-04  Akim Demaille  <address@hidden>

        Remove spurious initial empty lines.
        * data/glr.c, data/glr.cc, data/lalr1.cc, data/lalr1.java,
        * data/yacc.c: End the @output lines with an @.