* internalcoff.h (SYMNMLEN, FILNMLEN, DIMNUM): Define these

* internalcoff.h (SYMNMLEN, FILNMLEN, DIMNUM):  Define these
for internalcoff, separately from the various external coff's.
* amdcoff.h, bcs88kcoff.h, i386coff.h, intel-coff.h, m68kcoff.h,
m88k-bcs.h: Prefix SYMNMLEN, FILNMLEN, and DIMNUM with E_'s for
the external struct definitions.
* ecoff.h: Remove these #define's, kludge no longer needed.