[petsc-dev] improvement to ./configure

[Barry Smith]

    Matt,

    It would be nice when some user types --xxxx-yyyyyy_zzzz and they  
meant --xxxx-yyyyyy-zzzz it would give them a nice error message. This  
is made difficult by the fact that superlu_dist name as an underscore  
in it. Are there other special cases?

    Could we have BuildSystem barf with helpful error message whenever  
someone puts an _ instead of - except when allowed like superlu_dist?

    We semi-regularly waste time with petsc-maint messages of people  
who cannot distinguish _ from -

     Barry