security.

* mkconfig.rb: hide build path from rbconfig.rb.

* util.c (ruby_strtod, dtoa): initialize more variables for error
  handling.

* io.c (rscheck), marshal.c (w_nbyte, w_bytes, w_unique),
  (path2class, path2module): constified.

* pack.c (pack_unpack), process.c (rb_syswait): suppress warnings.

* suppress warnings on cygwin, mingw and mswin.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_7@16863 b2dd03c8-39d4-4d8f-98ff-823fe69b080e