unsigned buffer.
	* compressed_output.cc (zlib_compress): Use unsigned buffers,
	add zlib header.
	(zlib_compressed_suffix): Removed.
	(Output_compressed_section::set_final_data_size): Use unsigned
	buffers.
	* testsuite/Makefile.am (flagstest_compress_debug_sections):
	Fix linker invocation.
	(flagstest_o_specialfile_and_compress_debug_sections):
	Likewise.
	* testsuite/Makefile.in: Regenerated.