[Xcb] More pthread stubs.

[M Joonas Pihlaja]

On Tue, 22 Jun 2010, M Joonas Pihlaja wrote:

> Somehow we would need to convince automake that stubs.c should be 
> built not by the user (which is what BUILT_SOURCES seems to be saying 
> on a more careful reread of the manual) but by the developer before 
> rolling up a tarball.

Just a note to emphasize: clearly we don't want the user to need 
autoconf/m4 installed just to build pthread-stubs, right?

Joonas