Partially revert case insensitivity fixes.  Apparently REG_ICASE has
quite a severe performance impact.  Therefore make the compiled-in
default case sensitive again.  Only apply the run-time default setting
from CASE_SENSITIVE_MATCH to the verbs that offer options to set the
matching type -- ie.

   annotate
   check
   delete
   fetch
   info
   install
   lock
   query
   rquery
   search
   set
   version

I think the only way to fix this satisfactorily is to use a regex library
with a saner implementation of case insensitive matching (PCRE?)
Merge branch 'master' of github.com:freebsd/pkg