Make sure globals created by UBSan are not instrumented by ASan.

Summary:
This change adds description of globals created by UBSan
instrumentation (UBSan handlers, type descriptors, filenames) to
llvm.asan.globals metadata, effectively "blacklisting" them. This can
dramatically decrease the data section in binaries built with UBSan+ASan,
as UBSan tends to create a lot of handlers, and ASan instrumentation
increases the global size to at least 64 bytes.

Test Plan: clang regression test suite

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: cfe-commits, byoungyoung, kcc

Differential Revision: http://reviews.llvm.org/D4575