Add a gas configure option to select the default behaviour for the generation of debug sections - compressed or uncompressed.

	PR gas/19109
	* configure.ac: Add option --enable-compressed-debug-sections.
	This sets the default behaviour for compressing debug sections.
	* as.c (flag_compress_debug): Define and initialise to
	COMPRESS_DEBUG_GABI_ZLIB if DEFAULT_COMPRESS_DEBUG is set.
	(show_usage): Indicate whether --no-compress-debug-sections
	or --compress-debug-sections is the default.
	* config/tc-i386.c (flag_compress_debug): Delete definition.
	* doc/as.texinfo (--nocompress-debug-sectionas): Update
	description.
	* NEWS: Announce the new feature.
	* config.in: Regenerate.
	* configure: Regenerate.