Updated Boost to latest 1.55.0

Shouldn't have any disadvantage because boost still has support
for e.g. GCC 3.3. Newest version should work better with newer
compilers (e.g. no warnings).

Reduced the number of changes in boost to two:
- Virtual dtor fix is not required anymore
- Removed #error which was aimed at producing compiler errors
  for removed dependencies. Because this internal boost is only
  meant to be used by Gromacs we shouldn't have to detect
  odd usage of BOOST_* defines.

Fixed two comipler warnings:
- Applied nvcc.path from https://svn.boost.org/trac/boost/ticket/9392
- Commented out unsed parameter

These warnings should be fixed in future boost versions but if not and
the changes have to be reapplied, check Gerrit for the diff. Patch Set 1
contains the unmodified version without the fixes.

Change-Id: I09179891f9979a5997171a579a6a552621a693df