crosperf: Fix index incrementing

Increment a file index when copying multiple files.
This fixes the issue when multiple perf.data files are copied from
the system_health.memory_desktop benchmark with profiling.

BUG=None
TEST=crosperf with system_health.memory_desktop and profiling enabled.

Change-Id: I7d00ec23a4fa595d6cd0df8fcc8b64cf7181f5dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2622963
Tested-by: Denis Nikitin <denik@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
2 files changed