Well, kinda... localtime.c still contains a bunch of Android-specific
hacks, as does strftime.c. But the other files are now exactly the same
as upstream.
This catches up with several years of bug fixes, and fixes most of the
compiler warnings that were in this code. (Just two remain.)
Bug: 1744909
Change-Id: I2ddfecb6fd408c847397c17afb0fff859e27feef
