Fixed compile errors

Fixed some compile errors. Please check especially the fix in cst_sct3.hpp carefully - I'm not sure if its correct. The lines were added by commit d1a6fea975 (https://github.com/simongog/sdsl-lite/commit/d1a6fea975955da11bfff5afb3d0594b181c359a#include/sdsl/cst_sct3.hpp) and removed one commit (1ab17a82d6) later (https://github.com/simongog/sdsl-lite/commit/1ab17a82d6a516af5d4d8e4a22af311bb76259da#include/sdsl/cst_sct3.hpp)