code review 4431064: install: convert GOROOT and GOBIN Windows-style paths t...

install: convert GOROOT and GOBIN Windows-style paths to Unix-like paths

GOROOT and GOBIN paths are used to build the Go toolchain and
programs.

To build a Go program on Windows, the paths should be valid Windows
full paths, starting with the drive letter and a colon e.g. C:\go\bin
or c:/go/bin.

On Windows, the Go toolchain is built using the MSYS/MinGW Unix-like
toolchain. MSYS knows that it must convert a Windows-like PATH to a
Unix-like path. MSYS does not know that it should convert
Windows-like GOROOT and GOBIN paths to Unix-like paths, so we
have to do the conversion.

Rob Pike's windows_path function has been revised to convert Windows
drive letters to lowercase.

Fixes issue 1734.
Fixes issue 1735.

[peterGo, 2011-04-25 15:43:32]

Hello rsc (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2011-04-25 15:46:41]

Thanks for fixing this, but there are too
many CLs about this topic.  Instead of
discussion and design via CL, could you,
Joe, and Alex all discuss this on golang-dev
in a non-CL thread, come to an agreement
about the solution, and then send a single CL?

The current status quo is that we are getting
CLs from all sides and I have no idea which
ones are duplicates of or supercede other ones.
Please have a separate discussion and send one.

Thanks.
Russ