Fix QT5 compatibility for Coin Control

Adapted from https://github.com/bitcoin/bitcoin/pull/3267
Update makefile.osx to prevent some compiling errors under osx 10.9

osx 10.9 changed the default stdlib to libc++. You may need to compile with libstdc++ to prevent some errors. At the same time, boost should be compiled use a cxxflag '-stdlib=libstdc++'
Litecoin: More straightforward SSE2 detection

- Move CPU capabilities detection from init.cpp to scrypt.cpp
- scrypt_1024_1_1_256_sp is defined as a macro: no need to check for SSE2
  every time it is used
- Test correctness of both scrypt-generic and scrypt-sse2
Upgrade gitian win32 to boost-1.55.

Fixes issue where all network activity just stops.
Litecoin: Release Notes for 0.8.6.2
Litecoin v0.8.6.2