rebaseall in new install before packaging it.

This matches what lazka did in the 20250209 i686 build after syncing.

make-msys2-installer

@@ -89,6 +89,7 @@ create_chroot_system() {
     pacman -S base --noconfirm --root "${_newmsys}"
     grep -F '[build32]' etc/pacman.conf || sed -i '/\[msys\]/i [build32]\nServer = https://github.com/jeremyd2019/msys2-build32/releases/download/repo\nSigLevel = Optional\n' etc/pacman.conf
     pacman -Q --root "${_newmsys}" > "${_thisdir}/msys2-base-${_arch}-${_date}.packages.txt"
+    MSYSTEM=MSYS chroot "${_newmsys}" usr/bin/rebaseall -p
   popd > /dev/null
 }