Initialize nccl_lib_path.

PiperOrigin-RevId: 218340343
diff --git a/configure.py b/configure.py
index ceaae63..42aab03 100644
--- a/configure.py
+++ b/configure.py
@@ -1182,6 +1182,7 @@
       if is_windows() or is_cygwin():
         nccl_install_path = cygpath(nccl_install_path)
 
+      nccl_lib_path = ''
       if is_windows():
         nccl_lib_path = 'lib/x64/nccl.lib'
       elif is_linux():