Avoid setting the visibility of refinement method entries

	Since refinement search is always performed, these entries should always
	be public. The method entry that the refinement search returns decides
	the visibility.

	Fixes [Bug #17822]
	---
	 test/ruby/test_refinement.rb | 22 ++++++++++++++++++++++
	 vm_method.c                  | 15 ++++++++++-----
	 2 files changed, 32 insertions(+), 5 deletions(-)