[3/3] LCD Density changer (credit NamlessRom)
SF: Support to determine if the non-virtual displays are secure

- Non virtual displays can be secure/non-secure
- Add a hook to query this info from the HWC.
- This info will be used by the clients/apps which want to present
  content only to physical displays that are secure
- HDMI is considered secure if it supports HDCP

Change-Id: I632e2fa2c8d9a75258a92043c1680fa4e05a354c
sf: Block SIGPIPE signal to avoid crash

Block SIGPIPE signal in surfaceflinger process during initialization.
This is required to avoid SIGPIPE crash when client closes the read
pipe fd in the other end.

Change-Id: I329d63ae9630c3dd76000d3b64d425a463c742e4
Merge https://github.com/Illusion2/android_frameworks_native into lp5.0