[nix] fix build of test on Ubuntu (14.04) where gtest install by apt and compile together with source code.
Added advice to compile with addition parameter to speed up process.
[MinGW] fix build ( tested on x32-4.8.1-release-posix-sjlj-rev5.7z from http://sourceforge.net/projects/mingwbuilds/files/host-windows/releases/4.8.1/32-bit/threads-posix/sjlj/ )
For https://www.libsdl.org/release/SDL2-devel-2.0.3-VC.zip and
http://code.google.com/p/googletest/downloads/detail?name=gtest-1.7.0.zip&can=2&q=
mark change at CMakeList.
Remove linking of mingw32 as they do not need and make build impossible.