Cygwin support

Cygwin support

Patch by Bert Belder.

BUG=v8:64
BUG=v8:964
BUG=v8:1029
Committed: http://code.google.com/p/v8/source/detail?r=6842

[piscisaureus, 2011-02-15 22:11:30]

This adds Cygwin support.

[piscisaureus, 2011-02-16 01:22:34]

Apparently the sampler still didn't work right, because Cygwin does not
(always?) supply a context when calling a signal handler. In the updated patch
the sampler from platform-win32.cc is used.

[Vyacheslav Egorov (Chromium), 2011-02-17 14:00:48]

almost looks good. 

I am a bit concerned about having Cygwin specific ifdef in platform.h

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc
File src/platform-cygwin.cc (right):

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc#newcode1
src/platform-cygwin.cc:1: // Copyright 2006-2008 the V8 project authors. All
rights reserved.
2011

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc#newco...
src/platform-cygwin.cc:74: return 0;  // Nothing special about cygwin
dot at the end of the comment.
cygwin -> Cygwin

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc#newco...
src/platform-cygwin.cc:307: // Nothing to do on Cygwin
dot at the end of the comment.

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc#newco...
src/platform-cygwin.cc:312: // Not supported on Cygwin
ditto

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc#newco...
src/platform-cygwin.cc:597: // On cygwin we use the same sampler implementation
as on win32
cygwin -> Cygwin
dot at the end.

http://codereview.chromium.org/6525028/diff/5004/src/platform-cygwin.cc#newco...
src/platform-cygwin.cc:701: data_->sampler_thread_ = CreateThread(NULL, 0,
SamplerEntry, data_, 0,
one argument per line or the whole call on the next line.

http://codereview.chromium.org/6525028/diff/5004/src/platform.h
File src/platform.h (right):

http://codereview.chromium.org/6525028/diff/5004/src/platform.h#newcode386
src/platform.h:386: #ifdef __CYGWIN__
I understand pthread_key_t is actually a pointer on Cygwin, so you can't cast it
to integer.

But still: can we somehow keep opaque nature of LocalStorageKey and avoid having
ifdef here?

[piscisaureus, 2011-02-17 16:17:21]

All addressed

[Vyacheslav Egorov (Chromium), 2011-02-17 16:45:40]

LGTM

Landed. Issues closed. 

Thanks for your contribution!