Fix t9200 on case insensitive file systems

Fix t9200 on case insensitive file systems

t9200 defines $CVSROOT where cvs should init its repository
$CVSROOT is set to $PWD/cvsroot.
cvs init is supposed to create the repository inside $PWD/cvsroot/CVSROOT

"cvs init" (e.g. version  1.11.23) checks if the last element of the path is
"CVSROOT", and if a directory with e.g. $PWD/cvsroot/CVSROOT already exists.

For such a $CVSROOT cvs refuses to init a repository here:
"Cannot initialize repository under existing CVSROOT:

On a case insenstive file system cvsroot and CVSROOT are the same directories
and t9200 fails.

Solution: use $PWD/tmpcvsroot instead of cvsroot $PWD/cvsroot

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Jeff King <peff@peff.net>