The standard Boost convention is for them to be called libboost_date_time and
libboost_system (with apropriate suffix then depending on type).
Did not touch the libboostthread library we build for Windows.
Add the ax_boost_thread.m4 file for completeness and possible use.
Document where the ax_boost*.m4 files come from.
Change-Id: Ib49bee71398d62c9760a1f8fd5c46be9f3400430
Modify our patches as necessary to match the updated boost sources. Drop
patches for which corresponding (or even identical) changes already are
present. Add a new boostsystem static library and use it in two places.
Change-Id: Ib59558feb56dab87a69c91b38caca8e7a9e9a22e
