It looks like the extension got messed up. If that's the case
renaming mkconfig.exe to mkconfig should at least build.
Either that, or configure.sh and/or sethost.sh set up for the wrong
host. When you select Ubuntu with the -u option, sethost.sh should set
the host to Windows, but the environment to Ubuntu.
After running configure.sh, can you please check the resulting .config
file? What is the HOST? What is the environment.
Even if those are correct, there could be something else wrong in the
armv7-m/Kconfig or Toolchain.defs that using the wrong settings.
There are lots of possbilities.
