tools: fix permissions of git-checkout.sh

23828:0d21b68f528b introduced a new scripts/git-checkout.sh, but it
had the wrong permissions.  chmod +x it, and add a blank line at the
end to make sure it actually gets updated.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

scripts/git-checkout.sh

@@ -44,3 +44,4 @@ elif test -f $ROOT/configure; then
 		--disable-kvm \
 		$IOEMU_CONFIGURE_CROSS
 fi
+