Try using ldflags to allow multiple definitions

Author: mcbarton

.github/workflows/Windows.yml

@@ -357,6 +357,7 @@ jobs:
         mkdir build 
         cd build
         $env:CPPINTEROP_BUILD_DIR="$env:PWD_DIR"
+        $env:LDFLAGS="-Wl,--allow-multiple-definition"
         echo "CPPINTEROP_BUILD_DIR=$env:CPPINTEROP_BUILD_DIR"
         echo "CPPINTEROP_BUILD_DIR=$env:CPPINTEROP_BUILD_DIR" >> $env:GITHUB_ENV  
         if ( "${{ matrix.cling }}" -imatch "On" )

lib/Interpreter/CMakeLists.txt

@@ -136,9 +136,6 @@ else()
     ${link_libs}
   )
   else()
-  set_target_properties(clangCppInterOp PROPERTIES
-  LINK_FLAGS "-Wl,--allow-multiple-definition"
-  )
   llvm_add_library(clangCppInterOp
     DISABLE_LLVM_LINK_LLVM_DYLIB
     CppInterOp.cpp