Fix unused var in stricter compilers (#7461)
Fix unused var in stricter compilers (#7461)

TEST=builds
google/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,iree-org/iree,google/iree,google/iree