parse_file: add filename with unknown symbol section

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
added support for 'A' symbols (absolute)

found in linux:

    `parse_file': ./arch/x86/boot/compressed/piggy.o: unknown sym type: '0000000000b67000 A z_extract_offset' (RuntimeError)

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>