Make clang host compiler use ${CHOST}.

Currently the host clang compiler is just 'clang'.  This CL makes
it 'x86_64-pc-linux-gnu-clang' ie. ${CHOST}-clang.

BUG=None
CQ-DEPEND=CL:489563
TEST=Testing in chromiumos-sdk and other trybots.

Change-Id: I2fb94f7c9fb5473dc6b10de788c5d72983fd597c
Reviewed-on: https://chromium-review.googlesource.com/503509
Commit-Ready: Caroline Tice <cmtice@chromium.org>
Tested-by: Caroline Tice <cmtice@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/sdk_lib/make_conf_util.sh b/sdk_lib/make_conf_util.sh
index 457d63e..1dd51df 100644
--- a/sdk_lib/make_conf_util.sh
+++ b/sdk_lib/make_conf_util.sh
@@ -99,8 +99,8 @@
   local cxx_string=""
 
   if [[ "${use_clang}" == "true" ]];  then
-      cc_string="CC=clang"
-      cxx_string="CXX=clang++"
+      cc_string='CC=${CHOST}-clang'
+      cxx_string='CXX=${CHOST}-clang++'
   fi
 
   ( echo "# Automatically generated.  EDIT THIS AND BE SORRY."