Don't use p_symbols with libtool

(this commit obviously breaks binary compatibility - clear your plugins)

configure.ac

@@ -5216,7 +5216,7 @@ dnl
 AS_IF([test "x${enable_shared_libvlc}" = "x"], [enable_shared_libvlc=no])
 AM_CONDITIONAL(BUILD_SHARED, [test "${enable_shared_libvlc}" != "no"])
 AM_CONDITIONAL(BUILD_PIC, [test "${build_pic}" = "yes" -o "${enable_shared_libvlc}" != "no"] )
-AS_IF([test "${enable_shared_libvlc}" != "no"], [
+AS_IF([test "${enable_shared_libvlc}" != "no" || test "${enable_libtool}" != "no"], [
   AC_DEFINE(HAVE_SHARED_LIBVLC, 1, [Define to 1 if libvlc is built as a shared library.])
 ])