Performance: Memory Optimizations.

The following optimizations are squashed in this change.

1. Enable Aggressive trim settings.

This change will enable aggressive trim settings for targets
up to 1GB. The change can be turned on/off from system properties.
By default, the properties are set for targets up to 1GB

Changes spread in to : ActivityManagerConstants.java

2. Propagate B-services to higher adj.

Depending on the inactivity of a service, move the B-services to
highest adj 906. Under memory pressure, these services will
be killed first ahead of cached apps which results in better
concurrency numbers with bg apps. Inactivity time and minumum
no of services to be maintained are configurable as system properties.
Improves concurrency.

Changes spread in to : ActivityManagerService.java

3. Postpone service restart during app launch.

In the android framework, when the service gets killed,
it will be rescheduled. Postpone the service restart if
the app is in process of startup. By Default this feature
is disabled. It can be enabled from build.prop of target.

Changes spread in to : ActiveServices.java

4. Performance: Make Cached apps limit configurable.

Set it via a target specific property
file. Allows flexibility to set the limit
based on device config.

Normally, setting a smaller value for
low-end device helps with performance.

Changes spread in to : ActivityManagerConstants.java

5. am: Add new flag to detect activity "launching" state

Use this flag to determine service re-schdelue delay and
exclude persistent services from delay.

CRs-Fixed: 783020 792122 879756 911145 2111356

Squash of following change-IDs:
    Change-Id: I233dddbff07e7ec1fe2ee96402fe1d411903beb5
    Change-Id: Ied6cfcc3d11951f32f18de680b0e3483db8e163e
    Change-Id: Ia86edf027e20df2c7aa6f34e3aa293f7a8e6f1fa
    Change-Id: I90a733d7134d86efffadf6815ce3d2944dd09419
    Change-Id: Id38d536ff375b57d69f5ca73265f62e85740fc04

Change-Id: I3b2110743a6e0dd1379aa3b7703b3a897db3f6e6