osmo-pcu[master]: RFC: remove this == NULL checks

Patch Set 1:

all checks of (this == null) will be eliminated by GCC >= 6.1 (https://gcc.gnu.org/gcc-6/changes.html, Value range propagation now assumes that the this pointer of C++ member functions is non-null. This eliminates common null pointer checks but also breaks some non-conforming code-bases (such as Qt-5, Chromium, KDevelop). As a temporary work-around -fno-delete-null-pointer-checks can be used. Wrong code can be identified by using -fsanitize=undefined.)

But given the "make check" failure we seem to expect that. You will need to move the null check before calling the function or create a method wrapper where the tbf pointer is passed so we can do the null check there.