get linked to nm.h, xm.h, and tm.h respectively by configure,
moved to appropriate config/<cpu> subdirectory.
* nm-sysv4.h, xm-sysv4.h, tm-sysv4.h, tm-sunos.h, nm-trash.h:
Native, host, and target files that are common across more than
one cpu architecture and included by one of the configured
native, host, or target files, get moved to config directory.
Change svr4 references to sysv4.
* source.c: Move declaration of external function index to
front of file so it is in scope for all references.
* utils.c (error, fatal): Make definitions consistent with
defs.h declarations (declared as "volatile void").
