cc/gcc: add preliminray support for 4.8

This means:
- introduce the new symbols for 4.8
- do not always select PPL if graphite is selected

Reported-by: "Plotnikov Dmitry" <leitz@ispras.ru>
[Dmitry did a preliminray patch to add gcc-4.8 support,
which this patch is inspired from]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

reporter_name="Thomas Petazzoni"

reporter_url="http://www.free-electrons.com/"

reporter_comment="Very basic testing only"