PR28530, Hang in objdump on machine with 196GB RAM

PR28530, Hang in objdump on machine with 196GB RAM

Investigating the PR28530 testcase, which has a fuzzed compression
header with an enormous size, I noticed that decompress_contents is
broken when the size doesn't fit in strm.avail_out.  It wouldn't be
too hard to support larger sizes (patches welcome!) but for now just
stop decompress_contents from returning rubbish.

	PR 28530
	* compress.c (decompress_contents): Fail when uncompressed_size
	is too big.
	(bfd_init_section_decompress_status): Likewise.