scripts: fix missing space when using CT_EXTRA_FLAGS_FOR_HOST

CT_EXTRA_FLAGS_FOR_HOST needs a preceding space to separate it from
any other options that have already been set.

Signed-off-by: Michael Hope <michael.hope@linaro.org>

 python

 import sys

 sys.path.insert(0, '@@PREFIX@@/share/gcc-@@VERSION@@/python')

 from libstdcxx.v6.printers import register_libstdcxx_printers

 register_libstdcxx_printers (None)

 end