Install only the tools that were actually built so a missing slang or Z3
frontend no longer aborts the merge, and drop the upstream check-mlir
stage whose mlir-runner JIT tests need shared runtime libs that our
static build does not expose.
Closes: https://bugs.gentoo.org/977442
Closes: https://bugs.gentoo.org/977441
Signed-off-by: Huang Rui <vowstar@gmail.com>