Add back RE2 to the manifest.

RE2 is a dependency of gRPC starting with version 1.31.

Bug: 279548314
Test: presubmit
Change-Id: Id31754402d81786c0108a81d39f47935099cf78a
Merged-In: I2f9adba77a0bc5b7bc26e3d116143b8a39a89094
1 file changed
tree: c074a49be56084c0bce197eb4a754be83c436d0e
  1. default.xml
  2. GLOBAL-PREUPLOAD.cfg
  3. OWNERS