Revert "temp workaround BigDecimal division issue [Bug #9316]"

This reverts commit 1e778b3b207394d2dcbe9570d4434fcf41345acf.

Please see ruby/ruby@e7fe564 for the official patch
* ext/bigdecimal/bigdecimal.c (BigDecimal_divide): Add an additional
  digit for the quotient to be compatible with bigdecimal 1.2.1 and
  the former.  [ruby-core:59365] [#9316] [#9305]

* test/bigdecimal/test_bigdecimal.rb: tests for the above change.

* ext/bigdecimal/bigdecimal.gemspec: bigdecimal version 1.2.4.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44588 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Merge pull request #11 from zzak/bigdecimal_division_bug_9316

Bigdecimal division fix for bug#9316