[asan] Make vector asan annotations exception-friendly

Fix vector asan annotations with RAII.
Add a test.
Also, remove one dead function.
Review: http://reviews.llvm.org/D4170



git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@216995 91177308-0d34-0410-b5e6-96231b3b80d8