signal_handler_caller.
* tm-68k.h (FRAME_{CHAIN,SAVED_PC}): Deal with sigtramp.
* tm-hp300bsd.h: Define SIGTRAMP_{START,END} not IN_SIGTRAMP.
* inferior.h (IN_SIGTRAMP): Definition moved from infrun.c.
Use SIGTRAMP_START if defined.
* infcmd.c (step_1): Use SIGTRAMP_{START,END} if needed.
* infrun.c (wait_for_inferior): Check IN_SIGTRAMP before SKIP_PROLOGUE.
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.