Imported map-util.h from or-tools.
Imported map-util.h from or-tools.

okdave/gjstest,aungzanbaw/gjstest,okdave/gjstest,google/gjstest,okdave/gjstest,google/gjstest,google/gjstest,okdave/gjstest,aungzanbaw/gjstest,google/gjstest,aungzanbaw/gjstest,aungzanbaw/gjstest