gapil/executor: Add accessor for the c-context.
gapil/executor: Add accessor for the c-context.

google/agi,google/gapid,pmuetschard/gapid,pmuetschard/gapid,pmuetschard/gapid,Qining/gapid,google/gapid,Qining/gapid,Qining/gapid,Qining/gapid,google/agi,pmuetschard/gapid,google/gapid,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,pmuetschard/gapid,google/agi,google/agi,google/gapid,google/agi,google/gapid,google/gapid,google/agi,Qining/gapid,pmuetschard/gapid,google/agi,google/gapid,google/agi,Qining/gapid,google/gapid,Qining/gapid