Check file size before getting section contents

Check file size before getting section contents

Don't check the section size in bfd_get_full_section_contents since
the size of a decompressed section may be larger than the file size.
Instead, check file size in _bfd_generic_get_section_contents.

	PR binutils/21665
	* compress.c (bfd_get_full_section_contents): Don't check the
	file size here.
	* libbfd.c (_bfd_generic_get_section_contents): Check for and
	reject a section whoes size + offset is greater than the size
	of the entire file.
	(_bfd_generic_get_section_contents_in_window): Likewise.