More fixes for readelf problems reading corrupt files.

More fixes for readelf problems reading corrupt files.

	PR binutils/17531
	* readelf.c (process_version_sections): If the read of the version
	def information fails, make sure that the external verdef data is
	not used.
	(get_dynamic_data): Do not attempt to allocate memory for more
	dynamic data than there is in the file.  If the read fails, free
	the allocated buffer.
	(process_symbol_table): Do not print dynamic information if we
	were unable to read the dynamic symbol table.
	(print_gnu_note): Do not print the note if the descsz is too
	small.