[libclc] [libclc] Move external-funcs.test to static file and use IR checks for .cl tests (PR #197151)

[Matt Arsenault via cfe-commits]

================
@@ -0,0 +1,14 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
+// REQUIRES: AMDGCN
----------------
arsenm wrote:

I'd rather not acquire yet another divergent REQUIRES name for the target. Can this stick with the usual amdgpu-registered-target like llvm? 

https://github.com/llvm/llvm-project/pull/197151