It as been bothering me a bit that we don't set CC and LD consistently
for the kernel make calls and this can lead to interesting bugs as the
kernel increases in complexity. Add them to EXTRA_OEMAKE so they're
always passed in. This makes everything slightly more consistent and
less likely to break in future.
(From OE-Core rev: afe8c318843e4033dcc07e4f10198df241d8e4f6)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>