toolchain-wrapper was not reinstalled. So rules toolchain-external-reinstall,
gcc-initial-reinstall, gcc-final-reinstall didn't work as expected.
In add, normalize variable name: s/TOOLCHAIN_BUILD_WRAPPER/TOOLCHAIN_WRAPPER_BUILD/
Signed-off-by: Jérôme Pouiller <jezz@sysmic.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>