[TSan] add a new option 'use_internal_symbolizer' that allows to choose...

[TSan] add a new option 'use_internal_symbolizer' that allows to choose between addr2line-based and llvm-based symbolizer w/o having to rebuild the runtime. This is hopefully a temporary solution that simplifies testing process. In the end, we should leave a single symbolizer.

llvm-svn: 159730