Avoid loading the dll when it's not necessary.

fix_torch.py

@@ -9,8 +9,16 @@
 for folder in torch_spec.submodule_search_locations:
     lib_folder = os.path.join(folder, "lib")
     test_file = os.path.join(lib_folder, "fbgemm.dll")
+    dest = os.path.join(lib_folder, "libomp140.x86_64.dll")
+    if os.path.exists(dest):
+        break
+
+    with open(test_file, 'rb') as f:
+        contents = f.read()
+        if b"libomp140.x86_64.dll" not in contents:
+            break
     try:
         mydll = ctypes.cdll.LoadLibrary(test_file)
     except FileNotFoundError as e:
         logging.warning("Detected pytorch version with libomp issue, patching.")
-        shutil.copyfile(os.path.join(lib_folder, "libiomp5md.dll"), os.path.join(lib_folder, "libomp140.x86_64.dll"))
+        shutil.copyfile(os.path.join(lib_folder, "libiomp5md.dll"), dest)