Adds -std=c++11 to the build flags for drcachesim. Adds handling of -std=c++11 in the client flags processing code (i#1820).
Switches all instances of std::map to std::unordered_map in drcachesim. Adds explicit sorting for printing histograms in the reuse_distance and reuse_time tools (yes it's still faster to be unordered as the print time is not on the critical path).
Issue: #2020 (closed) Fixes #1820 (closed)