[tsan] Add global symbolication support into DlAddrSymbolizer

`DlAddrSymbolizer` is used on OS X when we're running inside a sandbox that prevents us from spawning an external symbolizer. This patch adds support for symbolication of globals (implements `SymbolizeData`) for `DlAddrSymbolizer`.

Differential Revision: http://reviews.llvm.org/D14613

llvm-svn: 252899