[binutils-gdb] Fix building and testing dwarf debug section compression feature when zlib is not available.

[sergiodj+buildbot@redhat.com]

*** TEST RESULTS FOR COMMIT e2575e05e73c3b2f08a8b5f579a504ac6a45ad60 ***

Author: Nick Clifton <nickc@redhat.com>
Branch: master
Commit: e2575e05e73c3b2f08a8b5f579a504ac6a45ad60

Fix building and testing dwarf debug section compression feature when zlib is not available.
	PR gas/18087
gas/test	* gas/i386/dw2-compress-1.d: Allow the test to pass regardless of
	whether the .debug_info section was compressed on not.

bfd	* compress.c (bfd_compress_section_contents): Do not define this
	function if it is not used.