Draft: testsuite: Don't disable LLVM ways due to unversioned llc

Previously we would silently disable the LLVM testsuite ways when LLC is set to an unversioned llc executable (e.g. llc instead of llc-5.0). Presumably this was because we were lax in checking the LLVM version in configure. However, this is no longer the case and consequently this confusing behavior is no longer necessary.

Test Plan: Validate

Reviewers: angerman

Reviewed By: angerman

Subscribers: michalt, rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4333