merge revision(s) r46485: [Backport #9897]

	* ext/fiddle/extconf.rb: supply 0 to fill RUBY_LIBFFI_MODVERSION
	  with 3-digit.  libffi 3.1 returns just 2-digit.
	  [ruby-core:62920] [Bug #9897]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46609 b2dd03c8-39d4-4d8f-98ff-823fe69b080e