Enable AUXV and QPassSignals in gdb-remote for NetBSD

Summary:
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

Subscribers: #lldb

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D31146

llvm-svn: 298407