toolchain_util.sh: Fix _configure_sysroot CBUILD

The portage CBUILD and HOSTCC variables need to be set to the SDK host to get
a proper cross build when building target binaries.

Change _configure_sysroot to use the CBUILD environment variable to set the
CBUILD and HOSTCC variables of ${ROOT}/etc/portage/make.conf.  Also, fix up all
calls to _configure_sysroot to set the CBUILD environment variable.

Fixes setup_board failure when the host and target architectures differ.

Signed-off-by: Geoff Levand <geoff@infradead.org>

[marineam: fixed a copy/paste error]

build_library/catalyst_toolchains.sh

@@ -16,7 +16,8 @@ configure_target_root() {
     local cross_chost=$(get_board_chost "$1")
     local profile=$(get_board_profile "${board}")
 
-    CHOST="${cross_chost}" \
+    CBUILD="$(portageq envvar CBUILD)" \
+        CHOST="${cross_chost}" \
         ROOT="/build/${board}" \
         SYSROOT="/usr/${cross_chost}" \
         _configure_sysroot "${profile}"

build_library/toolchain_util.sh

@@ -187,7 +187,8 @@ _get_dependency_list() {
 
 # Configure a new ROOT
 # Values are copied from the environment or the current host configuration.
-# Usage: ROOT=/foo/bar SYSROOT=/foo/bar configure_portage coreos:some/profile
+# Usage: CBUILD=foo-bar-linux-gnu ROOT=/foo/bar SYSROOT=/foo/bar configure_portage coreos:some/profile
+# Note: if using portageq to get CBUILD it must be called before CHOST is set.
 _configure_sysroot() {
     local profile="$1"
 
@@ -279,7 +280,10 @@ install_cross_libs() {
         sudo="sudo -E"
     fi
 
-    CHOST="${cross_chost}" ROOT="$ROOT" SYSROOT="$ROOT" \
+    CBUILD="$(portageq envvar CBUILD)" \
+        CHOST="${cross_chost}" \
+        ROOT="$ROOT" \
+        SYSROOT="$ROOT" \
         _configure_sysroot "${CROSS_PROFILES[${cross_chost}]}"
 
     # In order to get a dependency list we must calculate it before