it conditionalized on 4.3 vs. 4.4.
* config/m68k/nm-hp300bsd.h: Move REGISTER_U_ADDR out of 4.3 and
4.4 sections; it was identical and now works for 4.4.
config files moved to an appropriate config/<cpu> subdirectory.
* nm-*, xm-*, tm-*: All native, host, and target files, which
get linked to nm.h, xm.h, and tm.h respectively by configure,
moved to appropriate config/<cpu> subdirectory.