build-ancient: Fix build with ancient gcc

The gcc from crosstools do not use the normal prefix. That caused that the builder used the system gcc instead.

GCC5 does not support retpoline nor plugins, so we have to disable those.

The driver IMX_PXP fails to build, disable it for now. But we have to look into it.

Fixes #48 (closed)

Signed-off-by: Ricardo Ribalda ribalda@chromium.org