Enable AUXV and QPassSignals in gdb-remote for NetBSD
NetBSD is an ELF platform and it uses Elf Auxiliary Vector like Linux and other modern BSDs.
While there enable QPassSignals for the NetBSD port as well.
Sponsored by <The NetBSD Foundation>
Reviewers: labath, kettenis, joerg, emaste
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D31146