Simplify has_unsupported_isle_instructions now that skip block is minimal

[avrabe]

Context

After PR #53, has_unsupported_isle_instructions only checks for Instruction::Unknown(_). The function still does recursive block traversal, but it's now equivalent to the simpler has_unknown_instructions helper.

TODO

Consider consolidating:

• Remove has_unsupported_isle_instructions and has_unsupported_isle_instructions_in_block
• Replace all call sites with has_unknown_instructions (which already exists and does the same flat check)
• Or: make has_unknown_instructions recursive like the unsupported version (it currently only checks top-level instructions)

Files

• loom-core/src/lib.rs: Both functions defined around line 6600, used in ~15 optimization passes