* test/ruby/test_file_exhaustive.rb
	  (TestFileExhaustive#test_stat_special_file): add a test.
	  GetFileAttributesExW fails to get attributes of special files
	  such as pagefile.sys.

	* win32/win32.c (check_valid_dir): for performance, check the path
	  by FindFirstFileW only if the path contains "...".

	* win32/win32.c (winnt_stat): use GetFileAttributesExW instead of
	  FindFirstFileW since GetFileAttributesExW is faster.
	  Based on the patch by Dusan D. Majkic.
	  [ruby-core:47083] [Feature #6845]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@36792 b2dd03c8-39d4-4d8f-98ff-823fe69b080e