* hash.c (rb_hash_shift): use st_shift if hash is not being iterated to
delete element without iterating the whole hash.
* hash.c (shift_i): remove function
* include/ruby/st.h (st_shift): add st_shift function
* st.c (st_shift): ditto
[Bug #8312] [ruby-core:54524] Patch by funny-falcon
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40457 b2dd03c8-39d4-4d8f-98ff-823fe69b080e