src/rt/release.sh: Teach it to build bash

src/rt/release.sh: Teach it to build bash

Bash builds fine with standard configure/make in our environment.

The only glitch is that msys sources must be cloned with
core.autocrlf=false, or else, as documented in mingw wiki[1] there will
be build failure in builtins/

I assume core.autocrlf is set to false in all msysgit developers setup,
because as described in dd6ab17a (Set default core.autocrlf=true):

"""
    Note, msysgit developers should override this changed default by
    explicitly setting core.autocrlf=false in msysgit and
    msysgit/git.  Msysgit is not (yet) a real cross-platform project
    but more like a Unix project.
"""

If relying on this tweak is not ok, I suggest to put core.autocrlf=false
as default in etc/gitconfig, and maybe tweak it to true when preparing
installer.

Configure options were taken from msys-build-bash in
bash-3.1.17-4-msys-1.0.16-src.tar.lzma .

[1] http://oldwiki.mingw.org/index.php/Build%20bash

Signed-off-by: Kirill Smelkov <kirr@landau.phys.spbu.ru>