[libclc] [libclc] Add initial LIT tests (PR #87989)

[Fraser Cormack via cfe-commits]

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@@ -1,3 +1,6 @@
-__kernel void foo(int *i) {
+// RUN: %clang -emit-llvm -S -o - %s | FileCheck %s
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frasercrmck wrote:

That's true, but I'm still sceptical that we can make the tests simple enough for `update_cc_test_checks` to be viable. We'd have to embed libclc further into the clang driver for it to work, given that it currently doesn't know where to find libclc libraries for each target, and we can't express the path to libclc libraries in LIT in such a way that `update_cc_test_checks` would handle it. I'm not convinced clang _should_ necessarily know about libclc. I don't think we should be tying libclc to any specific compilation model like OpenCL C.

https://github.com/llvm/llvm-project/pull/87989