merge revision(s) 44588: [Backport #9316]

	* 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://svn.ruby-lang.org/ruby/branches/ruby_2_1@44711 b2dd03c8-39d4-4d8f-98ff-823fe69b080e