configure.in: no crypt.h on FreeBSD 12
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57090 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: no crypt.h on FreeBSD 12
is declared in unistd.h. [ruby-core:78664] [Bug #13038]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57090 b2dd03c8-39d4-4d8f-98ff-823fe69b080e