Also scan NDK's unwanted symbols list (to show the things that we're
exporting but the NDK isn't. Symbols hidden in the NDK will be marked
with a *.
Add a -u (--unwanted) flag to disable the first two printed groups
(all symbols in bionic, all symbols in glibc). This is helpful when
wanting to grep in the list of unwanted symbols.
Finally, update the list of known differences between us and glibc.
Change-Id: I6fdb4126823098430454763c391bd8cd369a75bb
76212eeb53