compiler: Fork-exec into inode2filename as a subprocess

This adds a new flag --process-mode={out,in} to iorap.inode2filename.
Using --process-mode=out will cause inode2filename to fork into itself,
allowing the caller/callee to have distinct selinux domains.

iorap.cmd.compiler is defaulted to forking into inode2filename
(as is iorapd which itself forks into iorap.cmd.compiler).

Bug: 117840092
Test: iorap.inode2filename --process=mode=in --all
Test: iorap.inode2filename --process=mode=in <some-i-nodes>
Test: iorap.cmd.compiler --output-proto compiled.pb raw_trace.pb
Change-Id: I13e60de860d28d6a3759f37f0ca02333e9205d42
9 files changed