Update GURL_API to cover non-Windows platforms.
Update GURL_API to cover non-Windows platforms.

When GURL_DLL is set, we export any symbols tagged GURL_API.

Patch by Evan Martin <evan@chromium.org>


datacratic/DasDB,datacratic/DasDB,datacratic/DasDB,datacratic/DasDB,datacratic/DasDB