tree 40138fa339e5060338475cf85387a0ea374b8fbf
parent 55d04f39429778250fc99a71113d3356a65fc084
author David Hendricks <dhendrix@chromium.org> 1315347612 -0700
committer David Hendricks <dhendrix@chromium.org> 1315347612 -0700

Conditionally assign toolchain variables

tc-export apparently does not set the CROSS_COMPILE prefix for tools like gcc,
ar, etc. Instead, it seems to set the variables directly.

Conditionally assigning them in the Makefile with "?=" instead of "=" or ":="
makes cross compilation work for board overlays. With "=" instead of "?=",
compilation fails complaining that "atom" is not value for -mtune and -march.

BUG=none
TEST=Compiled for host (amd64), x86-generic and tegra2_seaboard

Change-Id: I9ddb2eb769d53be3ade5e325e9b83f343b9b19ba