rename some base _linux files to _posix so that others can use it too

rename some _linux files to _posix and introduce os_bsd

The os_bsd variable is only available on FreeBSD and OpenBSD.
Later on others like NetBSD and DragonflyBSD can be added.
This variable was introduced in order to have shorter
conditions in the gyp files.

BUG=
TEST=compile

Patch by Robert Nagy <robert.nagy@gmail.com>;
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=109929

[Robert Nagy, 2011-11-14 11:32:06]

please review

[Mark Mentovai, 2011-11-14 13:48:27]

Seems fine, LGTM.

[commit-bot: I haz the power, 2011-11-14 13:59:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/robert.nagy@gmail.com/8567001/1008

[commit-bot: I haz the power, 2011-11-14 13:59:29]

Presubmit check for 8567001-1008 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit Messages **
If this change has an associated bug, add BUG=[bug number].

** Presubmit Warnings **
New code should not use wstrings.  If you are calling an API that accepts a
wstring, fix the API.
    base/sys_string_conversions_posix.cc:14
    base/sys_string_conversions_posix.cc:19
    base/sys_string_conversions_posix.cc:22
    base/sys_string_conversions_posix.cc:32
    base/sys_string_conversions_posix.cc:36
    base/sys_string_conversions_posix.cc:42
    base/sys_string_conversions_posix.cc:102
    base/sys_string_conversions_posix.cc:116
    base/sys_string_conversions_posix.cc:129
    base/sys_string_conversions_posix.cc:131
    base/sys_string_conversions_posix.cc:145

Presubmit checks took 1.0s to calculate.

[Robert Nagy, 2011-11-14 14:00:22]

On 2011/11/14 13:59:29, I haz the power (commit-bot) wrote:
> Presubmit check for 8567001-1008 failed and returned exit status 1.
> 
> Running presubmit commit checks ...
> 
> ** Presubmit Messages **
> If this change has an associated bug, add BUG=[bug number].
> 
> ** Presubmit Warnings **
> New code should not use wstrings.  If you are calling an API that accepts a
> wstring, fix the API.
>     base/sys_string_conversions_posix.cc:14
>     base/sys_string_conversions_posix.cc:19
>     base/sys_string_conversions_posix.cc:22
>     base/sys_string_conversions_posix.cc:32
>     base/sys_string_conversions_posix.cc:36
>     base/sys_string_conversions_posix.cc:42
>     base/sys_string_conversions_posix.cc:102
>     base/sys_string_conversions_posix.cc:116
>     base/sys_string_conversions_posix.cc:129
>     base/sys_string_conversions_posix.cc:131
>     base/sys_string_conversions_posix.cc:145
> 
> Presubmit checks took 1.0s to calculate.

I did not touch this because i don't really grok that code.

[Mark Mentovai, 2011-11-14 19:15:48]

Committed r109929 after fixing the copyright year in
base/sys_string_conversions_posix.cc.