Revert "Makefile: add support for gcc 4.9.x"

This reverts commit a1b3d6f0ddf9a6f4eccaac976e56a59cf05e2cc3.
Revert "Fix some warnings when compiling with gcc 4.8.x/4.9.x"

This reverts commit bebd98481c29a8807b87ac351b82943455e88ad2.