Pr configure fixes for visual studio

Various fixes to make cmake to pass successfully on with -G "Visual Studio 12" generator. Also fixed one test case linking problem with poclu when compiling on Ubuntu with self compiled llvm 3.5.
On Windows clang is pretty much usable to only for compiling stuff to bytecode or to object files, but for fully linking executables linker from visual studio is needed. So it is easier to do these tests with running them in lli.