[libclc] [libclc] Fix commands in compile_to_bc are executed sequentially (PR #130755)

[Wenju He via cfe-commits]

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@@ -63,13 +65,15 @@ function(compile_to_bc)
       ${ARG_DEPENDENCIES}
     DEPFILE ${ARG_OUTPUT}.d
   )
+  add_custom_target( ${ARG_TARGET} DEPENDS ${ARG_OUTPUT}${TMP_SUFFIX} )
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wenju-he wrote:

> This is still better than what we've got so maybe we can keep an eye on it and see if we have any parallel build issues stemming from .ll files, and we can adjust as needed.

yeah, I agree

https://github.com/llvm/llvm-project/pull/130755