refactor common parts of unicode normalization functions into unicode_normalize_common
In string.c, refactor the common parts (requiring of unicode_normalize/normalize.rb,
check of number of arguments) of the unicode normalization functions
(rb_str_unicode_normalize, rb_str_unicode_normalize_bang, rb_str_unicode_normalized_p)
into the new function unicode_normalize_common.
refactor common parts of unicode normalization functions into unicode_normalize_common
In string.c, refactor the common parts (requiring of unicode_normalize/normalize.rb,
check of number of arguments) of the unicode normalization functions
(rb_str_unicode_normalize, rb_str_unicode_normalize_bang, rb_str_unicode_normalized_p)
into the new function unicode_normalize_common.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58558 b2dd03c8-39d4-4d8f-98ff-823fe69b080e