Revert "simplify external module check with macro"

Reverting this because it breaks a lot of stuff

This reverts commit a2dbcf1e.

m4/libo_externals.m4

-# -*- Mode: makefile-gmake; tab-width: 4; indent-tabs-mode: t -*-
-#
-# This file is part of the LibreOffice project.
-#
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-#
-AC_DEFUN([libo_PUBLISH_MODULE],
-[
-    true
-    AC_SUBST([SYSTEM_$1])
-    AC_SUBST([$1_CFLAGS])
-    AC_SUBST([$1_LIBS])
-])
-
-AC_DEFUN([libo_CHECK_SYSTEM_MODULE], [
-AC_MSG_CHECKING([which $1 to use])
-if test "$with_system_$1" = "yes"; then
-    AC_MSG_RESULT([external])
-    SYSTEM_$2=YES
-    PKG_CHECK_MODULES([$2], [$3])
-else
-    AC_MSG_RESULT([internal])
-    SYSTEM_$2=NO
-    BUILD_TYPE="$BUILD_TYPE $2"
-fi
-    libo_PUBLISH_MODULE([$2])
-])
-# vim: set noet sw=4 ts=4: