camera/media: Support for legacy camera HALv1

Pre 7.0 camera HALv1 can not share its video buffers
across different processes, which requires us to
disable this security feature.

This change allows devices to re-integrate cameraserver
and mediaserver which is the first step to support older
prebuilt camera HALs. A follow-up change will add back
support for legacy buffer handling.

To enable:
TARGET_HAS_LEGACY_CAMERA_HAL1 := true
media.stagefright.legacyencoder=true
media.stagefright.less-secure=true

Change-Id: I4fcc8907ea235b7e83af26122b4da97ca5117816