message: Add `linkstatic` to reduce package size
  This fix adds `linkstatic = True` to reduce the whl package size (from 61M -> 52M)
diff: @@ -29,8 +29,8 @@ cc_binary(
  ],
  )
  -cc_binary(
  - name = "python/ops/_bigtable_test.so",
  +cc_library(
  + name = "bigtable_test",
  srcs = [
  "kernels/test_kernels/bigtable_test_client_op.cc",
  "ops/bigtable_test_ops.cc",
  @@ -40,7 +40,7 @@ cc_binary(
  "-std=c++11",
  "-DNDEBUG",
  ],
  - linkshared = 1,
  + linkstatic = True,
  deps = [
  ":bigtable_lib_cc",
  ":bigtable_test_client",
  