Do not load libomptarget if there's no gpu to avoid error

Author: ggeorgakoudis

numba/openmp/__init__.py

@@ -480,6 +480,10 @@ def _init():
     if sys_platform.startswith("darwin") or sys_platform.startswith("win32"):
         return
 
+    # libomptarget errors out if gpu is not available.
+    if not numba_cuda.is_available():
+        return
+
     omptargetlib = llvm_libpath + "/libomptarget.so"
     if DEBUG_OPENMP >= 1:
         print("Found OpenMP target runtime library at", omptargetlib)