This CL updates roll_boringssl.go to make use of the changes to
//zircon/third_party/ulib/uboringssl to match this repo.  It also now
delays making commits until all changes are successful.

ZX-1991 #comment Fuchsia side support

Change-Id: Ie6cd654fa7fc8cc0afbf3917f243d3d2f261c113