[bind10-dev] require libboost_thread?

[JINMEI Tatuya / 神明達哉]

I noticed lib/nsas/tests recently merged trunk required a compiled
boost library, libbost_thread, and it caused a build failure on my
system.  I then realized we the test program could compile without the
library, so I simply removed the requirement from Makefile.am (r3844).

But I think the fact that we once tried to require a compiled boost
library warrants a discussion.  Are we planning to use the boost
thread library eventually?  Requiring a compiled version of boost
library raises the introduction bar significantly and we've been
carefully avoiding that so far (we dropped boost.python partly for
this reason, and we switched to the non boost version of ASIO exactly
for this reason).  If the cost-benefit tradeoff is convincing we might
accept some exceptions, but I believe we should discuss each case
community-wide before making the decision.

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JINMEI, Tatuya