buildgcc: Fix up cross GCC building

Add a missing line-break escape and, rather cosmetic, guard execution of
$CXX which we allow but don't force to be set.

Change-Id: Icf6d3b7de4b7999b8214489f28997964c490d1e9
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/21307
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
1 file changed