Register NetBSD/i386 in AddressSanitizer.cpp

Summary:
Ship kNetBSD_ShadowOffset32 set to 1ULL << 30.

This is prepared for the amd64 kernel runtime.

Sponsored by <The NetBSD Foundation>

Reviewers: vitalybuka, joerg, kcc

Reviewed By: vitalybuka

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46724

llvm-svn: 332069