[incfs] Add methods to "steal" fds out of the control

This will allow for much simpler binder calls without extra
duping

Bug: 153704006
Test: libincfs-test
Change-Id: If0837b4d2c05e884a76d4c28a4f53cf7766f04ce
Merged-In: If0837b4d2c05e884a76d4c28a4f53cf7766f04ce
5 files changed
tree: 12e68fc39d5dca0a6731e7fd620a0f950e36fba8
  1. incfs/
  2. libdataloader/
  3. .clang-format
  4. PREUPLOAD.cfg