[lldb] [Process/NetBSD] Use global enable bits for watchpoints

Set global enable bits (i.e. bits 1, 3, 5, 7) to enable watchpoints
on NetBSD rather than the local enable bits (0, 2, 4, 6).  The former
are necessary for watchpoints to be correctly recognized by the NetBSD
kernel.  The latter cause them to be reported as trace points.

Differential Revision: https://reviews.llvm.org/D63792

llvm-svn: 364781