Remove unnecessary copy in host_calls.cc
Remove unnecessary copy in host_calls.cc

The std::string constructor makes a copy.

PiperOrigin-RevId: 258604425
Change-Id: I7f7443d912d48af3fd28161ac2df11668a22501e

google/asylo,google/asylo,google/asylo,google/asylo,google/asylo,google/asylo