functions.sh: set host compiler when cross-compiling

We chose to use kernel style HOST* instead of the gcc's
*_FOR_HOST.

functions.sh.in

@@ -133,6 +133,13 @@ readconfig() {
 		# setup cross-compiler
 		if [ -z "$CROSS_COMPILE" ]; then
 			export CROSS_COMPILE="${CHOST}-"
+			export HOSTCC="$CC"
+			export HOSTCXX="$CXX"
+			export HOSTLD="$LD"
+			export HOSTCPPFLAGS="$CPPFLAGS"
+			export HOSTCXXFLAGS="$CXXFLAGS"
+			export HOSTCFLAGS="$CFLAGS"
+			export HOSTLDFLAGS="$LDFLAGS"
 			export CC=${CROSS_COMPILE}gcc
 			export CXX=${CROSS_COMPILE}g++
 			export LD=${CROSS_COMPILE}ld