[Libomptarget] Do not pass 'nogpulib' to the non-LTO Nvidia tests (#70327)

Summary:
For the other tests we pass `-nogpulib` to ensure that we set up the
needed libraries correctly. However, this caused problems for the
non-LTO build and test of Nvidia systems. In general this is because we
would do a separate compile of the libomptarget device runtime and then
link in that cubin. This exercised the runtime in a lot of ways it's not
used to, since doing things this way was hardly expected or tested. This
patch disables it only for the Nvidia non-LTO build so that we still get
the effect of `--liboimptarget-nvptx-bc-path` rather than ignoring it.

Author: jhuber6

openmp/libomptarget/test/lit.cfg

@@ -128,7 +128,8 @@ elif config.operating_system == 'Darwin':
     config.test_flags += " -Wl,-rpath," + config.library_dir
     config.test_flags += " -Wl,-rpath," + config.omp_host_rtl_directory
 else: # Unices
-    config.test_flags += " -nogpulib"
+    if config.libomptarget_current_target != "nvptx64-nvidia-cuda":
+        config.test_flags += " -nogpulib"
     config.test_flags += " -Wl,-rpath," + config.library_dir
     config.test_flags += " -Wl,-rpath," + config.omp_host_rtl_directory
     config.test_flags += " -Wl,-rpath," + config.llvm_lib_directory