Workaround for missing Content-Length information

Under some scenarios, certain webservers or proxies will miss
the `Content-Length` header that is used by the progress bar
component, causing the download task to abort.

This workaround was promosed in the mailing list and is hard to
reproduce.
Upgrade RubyGems to version 1.8.29

This one is used by Ruby 1.8.x and 1.9.x so an update to latest
available in the 1.8.x series was recommended.
Upgrade Ruby 2.0.0 to patchlevel 576

Results of `make check`:

https://gist.github.com/luislavena/242bfe198d4ec7e7a69b
Update Ruby 2.1 to version 2.1.3

Results of `make check`:

https://gist.github.com/luislavena/3ca45d084dea3f4c6667
Prepare releases
Add mingw64 4.8.2-rev0 x86 and x64 support
Only add DLDFLAGS for relevant DevKit's

Current GCC 4.8.x compilers add an implicit dependency to the libgcc
support library to msvcrt-rubyXYZ.dll. This overly complicates
installs and creates additional support concerns. Adding -static-libgcc
to configure's DLDFLAGS "fixes" this GCC behavior. Rather than
hard-coding DLDFLAGS for every build, set only when appropriate.

NOTE: while generic to 4.8.x, the DevKit version matching regex must
be updated to support future GCC versions if this GCC behavior persists.
Upgrade mingw64-{32,64}-4.8.2 to rev 1
Update mingw64-{32,64}-4.8.2 to rev2
Update mingw64-{32,64}-4.8.2 to rev3
Update mingw64-{32,64}-4.8.2 to rev4
Add mingw64-{32,64}-4.9.0 rev1 support
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 missing host option of x86_64 build
Add patch to MSYS2 based DevKit

The MSYS2 based patch utility embeds the manifest required to
prevent UAC issues on Windows systems.
Update mingw64-{32,64}-4.9.0 to rev2
Add mingw64-{32,64}-4.9.1 rev0 support