libbacktrace: minor fixes for zstd decompression

	* elf.c (elf_zstd_read_fse): Call elf_fetch_bits after reading
	bits, not before.  Add unlikely for error case.
	(elf_zstd_offset_table): Regenerate.
	(elf_zstd_read_huff): Clear 13 entries in weight_mark, not 12.
	(elf_zstd_read_literals): For a single stream adjust by
	total_streams_size, not compressed_size.