--program-prefix.

* configure.in: don't generate ext/extmk.rb.

* Makefile.in: execute directly $(srcdir)/ext/extmk.rb.
  remove -Cext option, "Dir::chdir 'ext'" in ext/extmk.rb.

* {win32,bccwin32}/Makefile.sub: ditto.

* instruby.rb: ditto.

* ext/extmk.rb: renamed from ext/extmk.rb.in.

* lib/mkmf.rb (module Logging): create log files (mkmf.log)
  in each extension module directories.

* ext/extmk.rb: ditto.

* lib/mkmf.rb (macro_defined?): new method.

* ext/.cvsignore: remove extmk.rb.

* ext/*/.cvsignore: add "*.def".


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@2819 b2dd03c8-39d4-4d8f-98ff-823fe69b080e