Upgrade to OpenSSL 1.0.0n
Use msys2(32bit) instead of old msys

Parallel make hangs due to msys bug.
http://sourceforge.net/p/mingw/bugs/1950/

msys2 is updated version of msys and the bug seems to be fixed.
http://mingw-users.1079350.n2.nabble.com/Status-of-MSYS2-td7582391.html

We pick up msys2 minimal dependencies to build ruby.
Need to set MSYSTEM=MINGW32 environment variable.

Default value of MSYSTEM is changed with msys2.
http://sourceforge.net/p/msys2/tickets/4/
Pass make options by MAKE_OPT environment variable

We can pass -jN to make for build speedup.
Replace mingw/gnuwin32 packages to msys2
Add /etc/fstab to remove cygdrive prefix

`/cygdrive` prefix may cause failures of installing gems.
Bump msys2 2.0.16196.25874b1-1-i686

- `sh.exe` crashes with latest `msys2-runtime` for some reason.
  We add filesystem package to fix `sh.exe` crash.

- remove `resources/devkit/fstab` since filesystem package
  contains `/etc/fstab`.

- keep msys2 default `/usr/bin` path to work properly.
  We modify PATH environment variable of devkit settings.

- `msys-unistring-2.dll` causes an error at fork while buiding ruby.
  We run rebase `msys-unistring-2.dll` to fix the error.