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
diff --git a/libs/androidfw/Android.mk b/libs/androidfw/Android.mk
index bb79f27..c06b144 100644
--- a/libs/androidfw/Android.mk
+++ b/libs/androidfw/Android.mk
@@ -38,7 +38,6 @@
     KeyCharacterMap.cpp \
     KeyLayoutMap.cpp \
     VelocityControl.cpp \
-    VelocityTracker.cpp \
     VirtualKeyMap.cpp
 
 commonSources:= \
@@ -74,7 +73,8 @@
 	BackupData.cpp \
 	BackupHelpers.cpp \
     CursorWindow.cpp \
-	InputTransport.cpp
+	InputTransport.cpp \
+	VelocityTracker.cpp
 
 LOCAL_SHARED_LIBRARIES := \
 	liblog \