toolchain-shar-extract.sh: better default install path for extensible SDK
Extensible SDK cannot be installed as root so by default offer to install it in
user's home directory under distro/distro_version replacing the normal SDK
version '+' char with a '_' as that's a restricted character for bitbake
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com> Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
