Fix issue with adbd patch striplevel

0001-Allow-adbd-to-be-ran-as-root.patch contains paths with 'a/', 'b/' prefixes which need to be stripped.

```
Applying patch 0001-Allow-adbd-to-be-ran-as-root.patch
can't find file to patch at input line 14
Perhaps you used the wrong -p or --strip option?
```

libsignon-qt5: Only apply a build workaround for 64bit hosts when actually building on a 64bit host. Closes https://github.com/AsteroidOS/asteroid/issues/44

systemd: Disable power key handling which would shut down the watch when pressed. MCE is there for that.

ngfd: Disable sound by default in the chat and information_strong feedbacks. Fixes vibration on watches without speakers

Remove Mesa 10.3.7 whose LLVMPipe is not compatible with OE Rocko's new LLVM version. Prepare a switch from VBox+VBoxGuestAdditions to QEMU+VirGL3D

packagegroup-qt5-toolchain-target: Don't depend on qtquick1, qtwebkit and qtquickcontrols2 but depend on most nemo-qml-plugins, qtvirtualkeyboard, mapplauncherd, qtmpris, glibmm and qml-asteroid so that the SDK can actually be used to build Asteroid apps

libhybris: Use the newer version provided by meta-smartphone rocko and don't use the wifi module which breaks every build

Adds an old-kernel-gcc-hdrs bbclass to provide the include/linux/compiler-gccX.h headers needed by 3.10 kernels when built with newer GCC versions (5, 6 and now 7 with the upgrade to rocko)