serverconfig: add CAMLI_PPROF_START

Change-Id: Ia3d3e021710f7681de7d43de87c236f8e37e992c
osutil: add CPUUsage function

Change-Id: Iba56be21be27f8786d8d7ca847ed9f2b7c3c1390
index: show corpus building CPU usage, disabled blob.Parse cache, size maps

Change-Id: I089053e8de46978573e4b5fe5cdc14ccac0d54a2