Tidy include/coff/external.h and internal.h

Tidy include/coff/external.h and internal.h

Mostly whitespace fixes and wrap of long comment lines, removal of block
comments and moving a few defines around.  Nothing much to see here,
but AUXESZ before union external_auxent is needed by the next patch.

	 * coff/external.h: Whitespace fixes, wrap long comment lines,
	 remove header style comments.  Move some defines.
	 (E_FILNMLEN): Remove #ifndef.
	 (_ETEXT): Don't define.
	 (SYMENT, AUXENT): Don't define, make them typedefs.
	 * coff/internal.h: Whitespace fixes, wrap long comment lines,
	 remove header style comments.  Move some defines.
	 (signed): Don't define.