roseapplepi: backport upstream patches to fix build with gcc 6

roseapplepi: backport upstream patches to fix build with gcc 6

The recent change to default to gcc 6 for the internal toolchain broke this
defconfig as the u-boot and linux kernel are too old to build with gcc 6.

Fit it by backporting the following commits:

- u-boot: 9b2c282b34 (compiler*.h: sync include/linux/compiler*.h with Linux 4.5-rc6)
- linux:  cb984d101b (compiler-gcc: integrate the various compiler-gcc[345].h files)

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>