SignalStrength: Hotfix TD-SCDMA take 2

The previous approach worked for 3G, but failed with TD-LTE. Let's
try something different to make them both work, and use the derpy
LTE checks only if a GSM signal is present.

Change-Id: I77e3b5a1e0f99df30c32b102918af418a20077c1
wm: Make the default menu longpress action configurable at build time

Do the same we do for home. For CDD validation, we need to switch
the menu and home longpress action, since Home must map to Google Now.

Change-Id: Iacfedf711d43f6637023c87c00e6c6b8b8a437dc