devtool: Fix source extraction for gcc shared source

If do_patch task is disabled then prepare do_configure dependencies to
fetch external sources and create symlink to ${S} in devtool workspace.

[YOCTO #13036]

Signed-off-by: Tomasz Dziendzielski <tomasz.dziendzielski@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>