[Offload][NFCI] Remove coupling to `omp` target for version scripting (#141637)

Summary:
This is a weird dependency on libomp just for testing if version scripts
work. We shouldn't need to do  this because LLVM already checks for
this. I believe this should be available as well in standalone when we
call `addLLVM` but I did not test that directly.

offload/CMakeLists.txt

diff --git a/offload/CMakeLists.txt b/offload/CMakeLists.txt
index 2dc8285..c7cafd1 100644
--- a/offload/CMakeLists.txt
+++ b/offload/CMakeLists.txt
@@ -322,14 +322,6 @@
 endif()
 endmacro()
 
-if(OPENMP_STANDALONE_BUILD OR TARGET omp)
-  # Check LIBOMP_HAVE_VERSION_SCRIPT_FLAG
-  include(LLVMCheckCompilerLinkerFlag)
-  if(NOT APPLE)
-    llvm_check_compiler_linker_flag(C "-Wl,--version-script=${CMAKE_CURRENT_LIST_DIR}/../openmp/runtime/src/exports_test_so.txt" LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
-  endif()
-endif()
-
 # OMPT support for libomptarget
 # Follow host OMPT support and check if host support has been requested.
 # LIBOMP_HAVE_OMPT_SUPPORT indicates whether host OMPT support has been implemented.

offload/liboffload/CMakeLists.txt

diff --git a/offload/liboffload/CMakeLists.txt b/offload/liboffload/CMakeLists.txt
index db12236..1b098bc 100644
--- a/offload/liboffload/CMakeLists.txt
+++ b/offload/liboffload/CMakeLists.txt
@@ -14,8 +14,8 @@
     target_link_libraries(LLVMOffload PRIVATE omptarget.rtl.${plugin})
 endforeach()
 
-if(LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
-    target_link_libraries(LLVMOffload PRIVATE "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/exports")
+if(LLVM_HAVE_LINK_VERSION_SCRIPT)
+  target_link_libraries(LLVMOffload PRIVATE "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/exports")
 endif()
 
 target_include_directories(LLVMOffload PUBLIC

offload/libomptarget/CMakeLists.txt

diff --git a/offload/libomptarget/CMakeLists.txt b/offload/libomptarget/CMakeLists.txt
index c5f5d90..93e684e 100644
--- a/offload/libomptarget/CMakeLists.txt
+++ b/offload/libomptarget/CMakeLists.txt
@@ -44,9 +44,8 @@
   ${LIBOMPTARGET_INCLUDE_DIR} ${LIBOMPTARGET_BINARY_INCLUDE_DIR}
 )
 
-if (LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
-  target_link_libraries(omptarget PRIVATE
-    "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/exports")
+if(LLVM_HAVE_LINK_VERSION_SCRIPT)
+  target_link_libraries(omptarget PRIVATE "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/exports")
 endif()
 
 # Define the TARGET_NAME and DEBUG_PREFIX.