build of 2.5.0 fails on Ubuntu 16.04

[peschue]

for several independent reasons

• boost version (1.58 does not work [problem with boost.m4 in particular program_options], neither does 1.64 [standard, problem with dlvhex code])
• gcc 5 [standard, maybe also boost.m4 issues, gcc 4.8 seems to work]