strip: Just admit we don't support stripping ar archives for now.

strip: Just admit we don't support stripping ar archives for now.

We try to handle (in-place) stripping of ar archives, but since elf_clone
doesn't really support cloning ar members and we don't handle reducing
the size of the members, moving the offsets of other members. This causes
crashes or writing garbage. Better to just admit that for now we don't
support stripping archives. Call error when we see an ELF_K_AR file.

https://bugzilla.redhat.com/show_bug.cgi?id=766156
https://lists.fedorahosted.org/pipermail/elfutils-devel/2009-August/000567.html

Signed-off-by: Mark Wielaard <mjw@redhat.com>