[libomptarget] Pass OMP_TARGET_OFFLOAD env variable through to tests

Useful for OMP_TARGET_OFFLOAD=MANDATORY when testing

Reviewed By: Meinersbur

Differential Revision: https://reviews.llvm.org/D111995

Author: JonChesterfield

openmp/libomptarget/test/lit.cfg

@@ -17,6 +17,9 @@ if 'CUDA_VISIBLE_DEVICES' in os.environ:
 if 'LIBOMPTARGET_DEBUG' in os.environ:
     config.environment['LIBOMPTARGET_DEBUG'] = os.environ['LIBOMPTARGET_DEBUG']
 
+if 'OMP_TARGET_OFFLOAD' in os.environ:
+    config.environment['OMP_TARGET_OFFLOAD'] = os.environ['OMP_TARGET_OFFLOAD']
+
 def append_dynamic_library_path(name, value, sep):
     if name in config.environment:
         config.environment[name] = value + sep + config.environment[name]