Add blurb about target necessities for readelf in bfdint.texi

[Ian Lance Taylor]

   Date: Wed, 24 May 2000 12:34:06 +0200
   From: Hans-Peter Nilsson <hans-peter.nilsson@axis.com>

   + While not a BFD component, you probably also want to make the binutils
   + program @samp{readelf} parse your ELF objects.  For this, you need to add
   + a dependency for @file{readelf.o} on @file{include/elf/@var{cpu}.h} in
   + @file{binutils/Makefile.am}, and code for @code{EM_@var{cpu}} as
   + appropriate in @file{binutils/readelf.c}.

Adding the dependency for readelf.o is incorrect.  The dependencies in
all of the binutils directories are built automatically, by using
`make dep-am'.

Ian