coreboot developer tools for windows Files

Starting with win-build-env-015.7z, msys2 replaces msys. Read about
msys2 here: https://sourceforge.net/projects/msys2/. Instructions
for recreating the build environment from scratch are included.

Also starting with win-build-env-015.7z is the addition of ARM
build tools. With this release, abuild can pass for all projects
except those requiring the riscv tool chain.

Some patches are needed in order for abuild to complete. See
how-to-build/how-to-abuild.txt for more information. Hopefully
the patches will be comitted soon and will no longer be needed.

This tool chain cannot build SeaBIOS version 1.7.5. Until 
SeaBIOS v1.8 is released, choose 'master' for SeaBIOS version
instead of the default of 1.7.5. 

This release defaults to gcc 4.9.2 for the x86, ARM, and AARCH64
cross compilers. The x86 build of gcc 4.8.3 is still included.
Edit go.bat to change the default compiler version. The gcc 4.9.2
tool chains are patched and built to fully support link time
optimization. If experiments are successful, a patch enabling gcc
link time optimization will be added.

---------- 05-18-2015 win-build-env-016.7z ----------
Once again, the latest coreboot code can be built from Windows.
Be sure to reapply the two patches after downloading a new
coreboot archive (see the last part of how-to-build\
setup-from-scratch.txt for details). Changes:
1) Update to latest msys2 and mingw gcc compilers. The coreboot
cross compilers are the same ones included in the last release.
2) Fix problems building latest coreboot code by adding objects
to libmingw32.a:
    a) hsearch.o/hsearch_r.o from libgw32c-0.4-lib
    b) glob from gnulib
3) Remove mkstemp from libmingwex.a due to incompatibility with
coreboot usage. Continue to use mkstemp from gnulib.
4) Add a dummy mman.h for coreboot fmap.c.

---------- 06-07-2015 win-build-env-017.7z ----------
Once again, the latest coreboot code can be built from Windows.
Changes:
1) Update to latest msys2 and mingw gcc compilers.
2) Update the coreboot cross compilers. A full set of gcc 4.9.2
coreboot cross compilers is now included: i386, x86_64,
aarch64, armv7-a, mipsel, and riscv.
Many coreboot projects build patch-free. Others require a single
patch (response-file.patch, included).
Abuild succeeds for 250 builds and fails on 3 (google/purin,
google/rush, google/rush_ryu). See included abuild-log.htm
for details.