Log Message:
sysutils/xcp: update to 0.12.1

v0.12.1
This is a testing and cleanup release:
 - Add testing with supported filesystems. Thanks to @hg.
 - Move vendored threadpool implementation to own crate see blocking-threadpool.
 - Misc. docs cleanup.

v0.12.0
 - Add feature-flag parblock; enabled by default.
 - Disable parblock build and test on Mac.
 - Re-enable torture-testing on Linux.

v0.11.0
 - Handle FIEMAP calls being unavailable on some FSs.

v0.10.2
 - No ChangeLog provided

v0.10.1
 - No ChangeLog provided

v0.10.0
 - Bump dependency to remove upstream vuln in tempfile (was only used in dev
   though).
 - Add additional guard for a file overwriting itself in the single-file-copy
   case.