qtsensors: Move Sensors.conf back to /etc/xdg/QtProject which is now the default QSettings::SystemScope. Fixes sensors backends loading

packagegroup-qt5-toolchain-target: Don't depend on the qtscript recipe which is not needed and doesn't seem to be well maintained (causes errors in builds)

qtbase: Compile qtbase 5.10 without support for getentropy which would otherwise produce binaries incompatible with our usual 3.10 kernels and result in ultra odd errors (no such file or directory, error -1) when linking with qtbase

qtvirtualkeyboard: Only enable lang-en_GB (instead of the default lang-all) because lipi-toolkit only supports this locale and handwriting characters recognition would stop working in asteroid-calendar when using a different, half-supported, language

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

qtbase: Give a default variable to QT_IM_MODULE to workaround the Agenda app staying blank under certain conditions

qtbase: respect ld-is-gold DISTRO_FEATURES (do it here before https://patches.openembedded.org/patch/140727/ gets upstreamed in meta-qt5)

bitbake meta-toolchain-qt5 was failing with the following error when
compiling qtwebkit:

  asteroid/build/tmp-glibc/sysroots/bass/usr/include/c++/6.2.0/cstdlib:75:25:
fatal error: stdlib.h: No such file or directory

This appears to be related to how qmake passes some include paths with
"-isystem" prefix [1,2]. This flag effects the internal header search
path order and seems to cause issues when compiling qtwebkit for the
sdk. By default QMAKE_CFLAGS_ISYSTEM = -isystem see [3]. This patch
resets QMAKE_CFLAGS_ISYSTEM to use -I instead for qtwebkit.

Additionally, the packagegroup-qt5-toolchain-target.bbappend adds/removes
some packages that were causing the do_populate_sdk to fail. These
changes were described in more detail here [4].

[1] http://lists.openembedded.org/pipermail/openembedded-core/2016-August/125952.html
[2] http://stackoverflow.com/questions/37218953/isystem-on-a-system-include-directory-causes-errors
[3] http://code.qt.io/cgit/qt/qtbase.git/tree/mkspecs/common/gcc-base.conf?h=5.6#n47
[4] http://ronan.lepage1.free.fr/gumstix-wiki/doku.php?id=asteroidos:clean_start

Adds Mer's fork of KCal which is outdated but needed by nemo-qml-plugin-calendar. Should be replaced later on by QtPIM

Adds Mer's fork of KCalCore which is outdated but needed by nemo-qml-plugin-calendar. Should be replaced later on by QtPIM