[lld] [lld][wasm] Clear lazyBitcodeFiles while resetting context (PR #118440)

[Sam Clegg via llvm-commits]

sbc100 wrote:

I guess we can land this without a test, especially since #78640 also didn't have any test.

@MaskRay do you know of any tests for context reuse/reset?

https://github.com/llvm/llvm-project/pull/118440