This change will allow traceur to pass a file descriptor to another app
in order to allow that app to process trace data files. E.g. in the use
case that someone would like to email the traces they collected and pass
the trace data files to gmail, this will now be permitted.

Bug:68126425
Test: Traceur can pass fd's to untrusted apps for processing
Change-Id: If0507b5d1f06fd8400e04bd60e06a44153dc59b7