i386msdos uninitialised read

Also reinstate ld i386aout for i386-msdos target, which doesn't build
otherwise.

bfd/
	* i386msdos.c (msdos_object_p): Don't access e_lfanew when that
	field hasn't been read.  Remove unnecessary casts.
ld/
	* Makefile.am (ALL_EMULATION_SOURCES): Reinstate ei386aout.c.
	Include ei386aout dep file.
	* Makefile.in: Regenerate.
	* po/BLD-POTFILES.in: Regenerate.