fix invalid conversion error with MinGW 4.8.1 in net.cpp

- fixes src\net.cpp:1601: Error:invalid conversion from 'void*' to
  'const char*' [-fpermissive] in a setsockopt() call on Win32 that was
  found by using MinGW 4.8.1 compiler suite
Bugfix: Move boost/version include from db.cpp to walletdb.cpp where BOOST_VERSION is used
makefile.mingw: Use normal boost libraries instead of debug for Windows

https://github.com/bitcoin/bitcoin/pull/2835#issuecomment-21231694
Bugfix: Include block creation and SSL options headings in usage
Merge pull request #2842 from luke-jr/bugfix_usage

Bugfix: Include block creation and SSL options headings in usage
Merge pull request #2836 from phelixbtc/patch-3

makefile.mingw: Use normal boost libraries instead of debug for Windows
Merge pull request #2826 from Diapolo/fix_mingw481

fix invalid conversion error with MinGW 4.8.1 in net.cpp
Merge pull request #2832 from luke-jr/bugfix_wdb_boostver

Bugfix: Move boost/version include from db.cpp to walletdb.cpp where BOOST_VERSION is used