add _TF_{MIN,MAX}_BAZEL_VERSION constants, to make these easier to find.

PiperOrigin-RevId: 253803878
diff --git a/configure.py b/configure.py
index 4c3c1bc..a475c02 100644
--- a/configure.py
+++ b/configure.py
@@ -49,6 +49,8 @@
 _TF_WORKSPACE_ROOT = ''
 _TF_BAZELRC = ''
 _TF_CURRENT_BAZEL_VERSION = None
+_TF_MIN_BAZEL_VERSION = '0.24.1'
+_TF_MAX_BAZEL_VERSION = '0.26.1'
 
 NCCL_LIB_PATHS = [
     'lib64/', 'lib/powerpc64le-linux-gnu/', 'lib/x86_64-linux-gnu/', ''
@@ -1391,7 +1393,8 @@
   # environment variables.
   environ_cp = dict(os.environ)
 
-  current_bazel_version = check_bazel_version('0.24.1', '0.26.1')
+  current_bazel_version = check_bazel_version(_TF_MIN_BAZEL_VERSION,
+                                              _TF_MAX_BAZEL_VERSION)
   _TF_CURRENT_BAZEL_VERSION = convert_version_to_int(current_bazel_version)
 
   reset_tf_configure_bazelrc()