Unbreak the Bazel build.

The build was broken because parallel_for.cc was deleted
and new file parallel_vector_ops.cc was added.

Fixes https://github.com/ceres-solver/ceres-solver/issues/1043

Change-Id: I5b7a03b97134da55d408e57747634a5943a0e0aa

bazel/ceres.bzl

diff --git a/bazel/ceres.bzl b/bazel/ceres.bzl
index ac102d9..2e5759e 100644
--- a/bazel/ceres.bzl
+++ b/bazel/ceres.bzl
@@ -95,9 +95,9 @@
     "manifold.cc",
     "minimizer.cc",
     "normal_prior.cc",
-    "parallel_for.cc",
     "parallel_invoke.cc",
     "parallel_utils.cc",
+    "parallel_vector_ops.cc",
     "parameter_block_ordering.cc",
     "partitioned_matrix_view.cc",
     "polynomial.cc",