Revert 894a65b0. abstract interpretation of for loops. there was some crashes and performance problems. I will fix those problems when I have time and recommit.
Fixed #3145 (False negative: no memory leak warning - return value of realloc(NULL,) ignored)
travis: check kernel as part of travis testing.

adds 2 more jobs (one for gcc, one for clang) which only compile Cppcheck with opimization CXXFLAGS to afterwards check a fixed version of the linux kernel to see if cppcheck crashes.