configure fails to detect fd_mask type on OS X
When running configure on trunk and/or 2.5.0, configure fails to detect that the type fd_mask exists.
As a consequence, HAVE_RB_FD_INIT gets no set to 1, which leads to rb_fdset_t not being defined.
The bug was introduced with this commit: https://github.com/ruby/ruby/commit/3215b27a9abd8de793cf517f32d8901fd421eb1c
merge revision(s) 61500: [Backport #14248]
fix fd mask detection on os x This was broken in r59440 (3215b27a9abd8de793cf517f32d8901fd421eb1c) [Bug #14248] From: Stefan Kaes <firstname.lastname@example.org>
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@61582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e