Fix torch check (#6402)

Author: loadams

op_builder/gds.py

@@ -36,7 +36,13 @@ def extra_ldflags(self):
         return super().extra_ldflags() + ['-lcufile']
 
     def is_compatible(self, verbose=False):
-        import torch.utils.cpp_extension
+        try:
+            import torch.utils.cpp_extension
+        except ImportError:
+            if verbose:
+                self.warning("Please install torch if trying to pre-compile GDS")
+            return False
+
         CUDA_HOME = torch.utils.cpp_extension.CUDA_HOME
         CUDA_LIB64 = os.path.join(CUDA_HOME, "lib64")
         gds_compatible = self.has_function(funcname="cuFileDriverOpen",