[libomptarget] Fix CUDA plugin build regression

After 3ecd38c, the Handler.getELFObjectFile routine is no
longer available.  Call ELF64LEObjectFile::create directly,
which should always be suitable for CUDA images.

Author: uweigand

openmp/libomptarget/plugins-nextgen/cuda/src/rtl.cpp

@@ -1160,7 +1160,7 @@ struct CUDADeviceTy : public GenericDeviceTy {
     // automatically so we must create it ourselves. The backend will emit
     // several globals that contain function pointers we can call. These are
     // prefixed with a known name due to Nvidia's lack of section support.
-    auto ELFObjOrErr = Handler.getELFObjectFile(Image);
+    auto ELFObjOrErr = ELF64LEObjectFile::create(Image.getMemoryBuffer());
     if (!ELFObjOrErr)
       return ELFObjOrErr.takeError();