Log Message:
Create template config file for Interix 3.x.

As part of this, do something special for xmesaP.h:  Because XShm.h does
exist on the Interix platform, and Mesa binaries were already buildable,
preserve the ABI by including XShm.h there and keeping the XShmSegmentInfo
field (with -DUSE_XSHM_HDRONLY) -- thus avoiding both flag day and revbump
sweep.  However, all XShm-using code remains turned off (no -DUSE_XSHM)
so that libGL will work.

Bump PKGREVISION of MesaLib only.