build/core: Add option to disable C++11 bits

Change-Id: I45294e8c19bf7cdf200b45fbd114ccd75c4e3ca9
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
Use gcc 4.8 as default
This is nice!
Don't build sample apns
Stop building musicfx
Disable ISO C++
Change default flags.

Credit to codefirex
Silence warnings.

Credit to vanir.