Added support for deprecated POSIX functions on Windows.
Summary: With the introduction of 8.0.1 We've stopped supporting in GHCi the use of POSIX functions under their deprecated names on Windows. This to be compatible with object and libraries from the most popular compilers on the platform (Microsoft and Intel compilers). However this brings a confusing disparity between the compiled and interpreted behavior since MingW-W64 does support the deprecated names. Also It seems clear that package writers won't update their packages to properly support Windows. As such I have added redirects in the RTS for the deprecated functions as listed on https://msdn.microsoft.com/en-us/library/ms235384.aspx. This won't export the functions (as in, they won't be in the symbol table of compiled code for the RTS.) but we inject them into the symbol table of the dynamic linker at startup. Test Plan: ./validate and make test TEST="ffi017 ffi021" Reviewers: thomie, simonmar, RyanGlScott, bgamari, austin, hvr, erikd Reviewed By: simonmar, bgamari Subscribers: RyanGlScott, #ghc_windows_task_force Differential Revision: https://phabricator.haskell.org/D2500 GHC Trac Issues: #12209, #12497, #12496