[sanitizer] Add a 'print_module_map' flag which prints modules with UUIDs on Darwin

This patch add a new sanitizer flag, print_module_map, which enables printing a module map when the process exits, or after each report (for TSan). The output format is very similar to what Crash Reporter produces on Darwin (e.g. the format of module UUIDs). This enables users to use the existing symbol servers to offline symbolicate and aggregate reports.

Differential Revision: https://reviews.llvm.org/D27400

llvm-svn: 291277