Move V8EXPORT definition to its own file

Move V8EXPORT definition to its own file

It is defined in each header of V8 public API and the definition already have some slight discrepancies. This CL makes all headers use the same definition.

BUG=None

[Yang, 2013-08-05 15:47:40]

https://codereview.chromium.org/22093003/diff/1/preparser/preparser.gyp
File preparser/preparser.gyp (right):

https://codereview.chromium.org/22093003/diff/1/preparser/preparser.gyp#newco...
preparser/preparser.gyp:53: '../include/v8-export.h',
this doesn't seem to be necessary.

[yurys, 2013-08-05 15:49:30]

https://codereview.chromium.org/22093003/diff/1/preparser/preparser.gyp
File preparser/preparser.gyp (right):

https://codereview.chromium.org/22093003/diff/1/preparser/preparser.gyp#newco...
preparser/preparser.gyp:53: '../include/v8-export.h',
On 2013/08/05 15:47:40, Yang wrote:
> this doesn't seem to be necessary.

Done.

[Sven Panne, 2013-08-05 16:26:41]

NOT LGTM. Wouldn't it be much simpler to keep the one-and-only definition in
include/v8.h and remove the #undef plus the copies of the CPP madness instead?

I don't think that #undef'ing something we #define'd before will help anybody. A
much more common, simple rule is to reserve a prefix for #defines in the
external headers (e.g. GL_ for OpenGL etc.).

Therefore I propose to drop this CL and make a differente CL that makes all our
macros have a V8_ prefix + drop copies of redundant macros. No #undefs involved.

[yurys, 2013-08-06 07:02:47]

On 2013/08/05 16:26:41, Sven Panne wrote:
> NOT LGTM. Wouldn't it be much simpler to keep the one-and-only definition in
> include/v8.h and remove the #undef plus the copies of the CPP madness instead?
> 
That was my initial intent but then I found that v8-preparser.h doesn't include
v8.h and decided that it would be better to move this into a separate header. If
we are OK with including v8.h into v8-preparser.h then I'll upload another CL
that does what you suggest.

> I don't think that #undef'ing something we #define'd before will help anybody.
A
> much more common, simple rule is to reserve a prefix for #defines in the
> external headers (e.g. GL_ for OpenGL etc.).
> 
Absolutely agree, this also would match what our approach in Chromium and Blink.

> Therefore I propose to drop this CL and make a differente CL that makes all
our
> macros have a V8_ prefix + drop copies of redundant macros. No #undefs
involved.

[yurys, 2013-08-06 07:42:08]

On 2013/08/05 16:26:41, Sven Panne wrote:
> NOT LGTM. Wouldn't it be much simpler to keep the one-and-only definition in
> include/v8.h and remove the #undef plus the copies of the CPP madness instead?
> 
> I don't think that #undef'ing something we #define'd before will help anybody.
A
> much more common, simple rule is to reserve a prefix for #defines in the
> external headers (e.g. GL_ for OpenGL etc.).
> 
> Therefore I propose to drop this CL and make a differente CL that makes all
our
> macros have a V8_ prefix + drop copies of redundant macros. No #undefs
involved.

Done. Please review at https://codereview.chromium.org/22363003/