build-sys: do not allow --enable static

Do the same as done in systemd by Cristian Rodríguez
<[email protected]>. We use private symbols, not namespaced. So
don't pretend we support static linking.
diff --git a/configure.ac b/configure.ac
index b8845d4..929eb7f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,6 +18,10 @@
 LT_INIT([disable-static pic-only])
 AC_PREFIX_DEFAULT([/usr])
 
+AS_IF([test "x$enable_static" = "xyes"],
+      [AC_MSG_ERROR([--enable-static is not supported by kmod])])
+
+
 #####################################################################
 # Program checks and configurations
 #####################################################################