Minor formatting change in pigweed.bzl.
Minor formatting change in pigweed.bzl.

This will be easier to deal with in code migrations.

Change-Id: Id3d62e3dbdce666c05547d298f82ef07f8724054

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed