[Bug #19985] Raise LoadError with the converted feature name

	`Kernel#require` converts feature name objects that have the `to_path`
	method such as `Pathname`, but had used the original object on error
	and had resulted in an unexpected `TypeError`.
	---
	 load.c                    | 14 +++++++++++---
	 test/ruby/test_require.rb | 26 +++++++++++++++++++++-----
	 2 files changed, 32 insertions(+), 8 deletions(-)