toolchain: adjust version check to allow for single numbers

toolchain: adjust version check to allow for single numbers

A gcc compiler, which was configured with
--with-gcc-major-version-only, will only return a single
number. (debian does this for example).

A simple modification allows the check to work with both
single numbers (eg. '9') and full versions (eg. '9.2.1').

Signed-off-by: Norbert Lange <nolange79@gmail.com>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>