[libomptarget][amdcgn] Add build dependency for llvm-link

[JonChesterfield]

Summary

Direct copy of D107156 with llvm-link instead of opt

[JonChesterfield]

If D107156 is the correct way to specify a dependency on opt then this should specify a dependency on llvm-link which is used in the same pipeline as opt. Relying on the reviewer's better understanding of our build system in this copy/paste patch, thanks!

[tianshilei1992]

Actually, the "true" correct way should be https://reviews.llvm.org/D107156#2918009. :-)

[protze.joachim]

In my latest re-build from main, I ran again into the issue with missing opt during runtime build.
I think, we need to declare the dependency to opt/llvm-link for the runtime/openmp target.

[JonChesterfield]

I've just been burned by this again but don't understand what the fix is. If not this, then what should we be doing here?

openmp/libomptarget/deviceRTLs/amdgcn/CMakeLists.txt

 foreach(mcpu ${mcpus})
   set(bc_files)
   add_cuda_bc_library(${cuda_sources})
 
   set(bc_libname lib${libname}-${mcpu}.bc)
   add_custom_command(
     OUTPUT ${bc_libname}
     COMMAND ${LINK_TOOL} ${bc_files} | ${OPT_TOOL} --always-inline -o ${OUTPUTDIR}/${bc_libname}
-    DEPENDS ${bc_files} opt)
+    DEPENDS ${bc_files} llvm-link opt)
 
   add_custom_target(lib${libname}-${mcpu} ALL DEPENDS ${bc_libname})
 
   install(FILES ${OUTPUTDIR}/${bc_libname}
      DESTINATION "${OPENMP_INSTALL_LIBDIR}"
   )
 endforeach()