Move VelocityTracker.cpp to target build only

VelocityTracker.cpp makes reference to property_get, which
doesn't make a lot of sense when compiling for the host.
Compile this file for the target only.

Keyboard.cpp: Remove unnecessary include file.

Change-Id: Iee9edd81953b2e7e815005770ce286a6ec586f20
2 files changed