Revert the changes to libxml.gyp in r52725....

Revert the changes to libxml.gyp in r52725.

Both libxml and its direct dependencies need to define
LIBXML_STATIC when libxml is a static library.  Right
now it is necessary to define this macro only on Windows,
but the macro is intended to be cross-platform.

R=evan
BUG=50048
TEST=Windows build log should not contain "locally defined
symbol XXX imported" linker warings such as:
libxslt.lib(numbers.obj) : warning LNK4049: locally defined symbol _xmlFree imported

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=53861

[wtc, 2010-07-26 22:44:51]

I didn't get the "macro defined twice" compilation errors
on Linux and Mac, so I'd like to give this a try.

[wtc, 2010-07-27 18:15:23]

I think I got to the bottom of this bug now.

Please review Patch Set 2.  (The other solution is to
patch libxml.h to define LIBXML_STATIC as 1.)  Thanks.

[Mark Mentovai, 2010-07-27 18:17:38]

LGTM

[Evan Martin, 2010-07-27 18:22:53]

http://codereview.chromium.org/3063009/diff/3001/4001
File third_party/libxml/libxml.gyp (right):

http://codereview.chromium.org/3063009/diff/3001/4001#newcode172
third_party/libxml/libxml.gyp:172: 'LIBXML_STATIC',
Should this also be 'LIBXML_STATIC='?

[Mark Mentovai, 2010-07-27 18:24:37]

evan@chromium.org wrote:
> http://codereview.chromium.org/3063009/diff/3001/4001
> File third_party/libxml/libxml.gyp (right):
>
> http://codereview.chromium.org/3063009/diff/3001/4001#newcode172
> third_party/libxml/libxml.gyp:172: 'LIBXML_STATIC',
> Should this also be 'LIBXML_STATIC='?

Shouldn’t need it, Wan-Teh told me the conflict was only with an
internal libxml header that dependents will never see.