merge revision(s) r46098: [Backport #9861]

	* vsnprintf.c (BSD_vfprintf): fix string width when precision is
	  given.  as the result of `memchr` is NULL or its offset from the
	  start cannot exceed the size, the comparison was always false.
	  [ruby-core:62737] [Bug #9861]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46611 b2dd03c8-39d4-4d8f-98ff-823fe69b080e