Report an error on objcopy/strip of sectionless binaries

All strip operations require section headers to be present, as do most
objcopy operations.  BFD is seriously confused by objects without
section info.  The error message added here is similar to the error
on attempting to strip/objcopy a zero length object.

	PR binutils/16811
	* objcopy.c (copy_object): Error if no sections.