layers.txt: bump oe-core, meta-oe, meta-smartphone revs a bit

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
layerman: Fetch tags before updating to new tag

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
layers.txt: bump meta-qt5 revision a bit

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
setup-env: set MACHINE=qemux86 by default

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>