libclc: Use echo rather than true for try_compile

When providing a fake compiler, libclc currently uses 'true' which does
not exist on Windows. Use echo instead as the no-op.

reviewer: jvesely
Differential Revision: https://reviews.llvm.org/D77163
GitOrigin-RevId: acf079006e6dbdd23300e9289cc8d8197aab5fb5
2 files changed