[xml] Threading support in libxml2

["Banginwar, Rajesh" <rajesh banginwar intel com>]

Hi Daniel,
        While going through some of the interfaces/macros etc, we came
across LIBXML_THREAD_ENABLED macro and xmlHasFeature interface. 

For LSB, I was thinking of requiring that the library support threading
regardless of the platform. E.g. even on single CPU IA32 platform, the
library should be enabled with threading support. Hence the LSB spec for
libxml2 will define the LIBXML_THREAD_ENABLED macro by default and the
rest assuming that macro... 

Does this make sense? Am I missing something here? 

Thanks for your help.

-Rajesh