Add support for -Duse_system_{libxml,libxslt,sqlite}=1 for...

Add support for -Duse_system_{libxml,libxslt,sqlite}=1 for
selection of the system version of those libraries on Linux.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=12521

[sgk, 2009-03-25 23:17:31]

I verified that use of -Duse_system_*=1 causes the right pkg-config command to
be run, but didn't go farther in debugging this.  The intent right now is just
to provide the right framework to show how this selection will occur with gyp. 
There may still be some necessary adjusting of settings to actually get things
building fully with system libs.

[Mark Mentovai, 2009-03-25 23:29:03]

LGTM.  Nice.  Real nice.

http://codereview.chromium.org/53076/diff/1/4
File third_party/sqlite/sqlite.gyp (right):

http://codereview.chromium.org/53076/diff/1/4#newcode197
Line 197: ['OS=="linux"', {
and !use_system_sqlite

[sgk, 2009-03-25 23:44:21]

http://codereview.chromium.org/53076/diff/1/4
File third_party/sqlite/sqlite.gyp (right):

http://codereview.chromium.org/53076/diff/1/4#newcode197
Line 197: ['OS=="linux"', {
On 2009/03/25 23:29:03, Mark Mentovai wrote:
> and !use_system_sqlite

?  I don't think so.  Seems like you should be able to build sqlite_shell
against either the system or hermetic versions of the sqlite library.