[asan] Don't print rows of shadow bytes outside shadow memory

Summary:
They might not be mapped on some platforms such as Win64.  In
particular, this happens if the user address is null. There will not be
any shadow memory 5*16 bytes before the user address. This happens on
Win64 in the error_report_callback.cc test case. It's not clear why this
isn't a problem on Linux as well.

Fixes PR35058

Reviewers: vitalybuka

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D39260

llvm-svn: 316589