geany: fix compile by removing extra check for c++ compiler

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
gthumb: add, taken from oe-core

This was removed in oe-core, so add it to meta-gnome.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
clutter-box2d: add, from oe-core

This was removed from oe-core but it's still useful, so add it to meta-oe.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
libgdata: add, from oe-core

libgdata was removed from oe-core, but it's still useful so add it to
meta-gnome.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>