icecc: Don't use icecc when INHIBIT_DEFAULT_DEPS is set
We don't have a compiler, so no icecc.
Silences a spew of warnings of the form:
do_configure: Cannot use icecc: could not get ICECC_CC or ICECC_CXX
Signed-off-by: Douglas Royds <douglas.royds@taitradio.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>