Documentation issues regarding AC_CONFIG_LINKS

[Nikolai Weibull]

In section 14.3, an example is given where AC_CONFIG_LINKS for the
same dest in a tag is used.  This isn’t allowed.  Thus, the example
needs to be changed to set a variable, for example,

     case $host in
       alpha*-*-*)  dither_os=alpha ;;
       powerpc*-*-*) dither_os=powerpc ;;
       *-*-*)        dither_os=generic ;;
     esac
     AC_CONFIG_LINKS([dither.c:$dither_os/dither.c])