[libclc] [libclc] Fix installed symlinks to be relative again (PR #149728)

[Fraser Cormack via cfe-commits]

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@@ -425,17 +425,21 @@ function(add_libclc_builtin_set)
       WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} )
   endif()
 
-  if(CMAKE_HOST_UNIX OR LLVM_USE_SYMLINKS)
-    set(LIBCLC_LINK_OR_COPY create_symlink)
-  else()
-    set(LIBCLC_LINK_OR_COPY copy)
-  endif()
-
   foreach( a IN LISTS ARG_ALIASES )
+    if(CMAKE_HOST_UNIX OR LLVM_USE_SYMLINKS)
+      cmake_path(RELATIVE_PATH libclc_builtins_lib
+        BASE_DIRECTORY ${LIBCLC_OUTPUT_LIBRARY_DIR}
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frasercrmck wrote:

Perhaps best leave it as you've got it here, as it's more robust to changes. If (some) files are moved in the future, everything would _likely_ still be relative to `LIBCLC_OUTPUT_LIBRARY_DIR` which is the thing that would most likely change. But I don't see the harm in having it as is.

https://github.com/llvm/llvm-project/pull/149728