devel/cvise: switch to USES=llvm

Instead of hand-declaring llvm dependencies, use USES=llvm instead.
This still needs USES=compiler for checking the base system's clang
version, as cvise 2.7.0 requires clang >= 15 to compile.

PR: 269935
Reported by: pkubaj
Approved by: maintainer timeout (2 weeks)
MFH: 2023Q1