* dir.c, file.c, io.c: use rb_sys_fail_path.

	* error.c: new functions to deal exceptions with string instances.

	* dir.c, file.c, io.c (rb_sys_fail_path): use rb_sys_fail_str.

	* test/ruby/test_literal.rb (TestRubyLiteral#test_special_const):
	  test for https://bugs.php.net/bug.php?id=61095


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@34814 b2dd03c8-39d4-4d8f-98ff-823fe69b080e