strip: Clean up a bit more after errors

strip: Clean up a bit more after errors

In some cases (late) errors would exit early without cleanup.  Set
result to 1 (failure) in those cases and fallthrough.  That way we
cleanup and might provide more hints to the user about what was wrong
with the file.

     * src/strip.c (handle_elf): Set result to 1 and fallthrough
     instead of return 1.

Signed-off-by: Mark Wielaard <mark@klomp.org>