Clean-up bookkeeping of in-flight RPCs (#3561)
Clean-up bookkeeping of in-flight RPCs (#3561)

Replace bitwise operation with proper increment/decrement
pmuetschard/gapid,google/gapid,pmuetschard/gapid,google/gapid,google/agi,pmuetschard/gapid,pmuetschard/gapid,google/gapid,google/agi,pmuetschard/gapid,pmuetschard/gapid,google/gapid,google/agi,pmuetschard/gapid,google/gapid,google/agi,google/agi,google/agi,google/agi,google/gapid,google/gapid,pmuetschard/gapid,google/gapid,google/agi