simpleperf: allow inferno to run from any dir.

Previously inferno.sh/.bat can only run from scripts/, this CL
removes the restriction.

Also add -o option to select report path.

Bug: http://b/32834638
Test: run test.py.
Change-Id: Ib1651dcd1beedac5be00249150e0b74fea906924
4 files changed