Fix install scripts failing when installing into the chroot

While everything can asume base is there, packages in base also
implicitely depend on the runtime (and maybe filesystem?), so install
them first.

Until now we were just lucky that pacman installed them in the right order.

Fixes #40

make-msys2-installer

@@ -113,6 +113,7 @@ create_chroot_system() {
     mkdir -p tmp
 
     eval "pacman -Syu --root \"${_newmsys}\"" | tee -a ${_log}
+    eval "pacman -S filesystem msys2-runtime --noconfirm --root \"${_newmsys}\"" | tee -a ${_log}
     eval "pacman -S base --noconfirm --root \"${_newmsys}\"" | tee -a ${_log}
     _result=$?
     if [ "${_result}" -ne "0" ]; then