Build eglib under none desktop Windows API family.

Initial work to build eglib under none desktop Windows API family. Classic
Windows API have been split into families and partitions in order to support
different subsets on different Windows platforms. In order to build against
other Windows targets/platforms Mono needs to follow these families/partitions
in order to successfully build where API’s have been removed/replaced. Since most
Mono platforms uses the Windows API signatures a new defined has been added to all
platforms, HAVE_CLASSIC_WINAPI_SUPPORT, used to decide what implementation to include.
On none Windows platforms this is always defined and on Windows platforms it follows the
winapifamily.h. In order to keep down regressions, the existing API’s are kept for HAVE_CLASSIC_WINAPI_SUPPORT
even if there are more modern replacements available.