Add RegionEqual function for older XFree86 versions.

Add RegionEqual function for older XFree86 versions.

Fixes bug : http://bugzilla.eng.vmware.com/show_bug.cgi?id=312853

When we added AUTOPAINT_COLORKEY capability to our VMware video driver,
region functions were used to keep track of colorkey painting.

REGION_EQUAL was one of them.

Unfortunately REGION_EQUAL was not present in regionstr.h shipped with XFree86 version
4.3.0.
This version is used by TurboLinux 10; causing X server to crash while playing videos.

REGION_EQUAL was added in revision 1.8 of regionstr.h and available for xfree86 version
4.3.99
onwards.
Reference:
http://cvsweb.xfree86.org/cvsweb/xc/programs/Xserver/include/regionstr.h.diff?r1=1.7&r2=1.8

When I compiled the existing code(without my change), I see a warning was generated
indicating REGION_EQUAL is not present.
Too bad we missed it.

This patch includes
1) Slightly modified version of miRegionEqual from miRegion.c
2) Some formating cleanup.