devel/cvise: import cvise-2.3.0

C-Vise is a super-parallel Python port of the C-Reduce. The port
is fully compatible to the C-Reduce and uses the same efficient
LLVM-based C/C++ reduction tool named clang_delta.

C-Vise is a tool that takes a large C, C++ or OpenCL program that
has a property of interest (such as triggering a compiler bug) and
automatically produces a much smaller C/C++ or OpenCL program that
has the same property. It is intended for use by people who discover
and report bugs in compilers and other tools that process C/C++ or
OpenCL code.

(wiz)