Needs <cerrno> include in tools/preproc/c_file.cpp
Merge C_ASM_DEP and DATA_ASM_DEP, NODEP and SCAN_DEPS can be overridden, add --no-print-directory to MAKEFLAGS in make_tools.mk (also removed some unused variables), add newline to help message in preproc.
For people who want to have dkPless builds in their repo.