[gupnp-dlna] Respect ACLOCAL_FLAGS

[Jens Georg <jensgeorg src gnome org>]

commit fc9accbfc873db88e9fc4f5150bc278ff6f553e5
Author: Jens Georg <mail jensge org>
Date:   Wed Aug 3 15:53:34 2011 +0200

    Respect ACLOCAL_FLAGS
    
    Issue reported by Lukasz Pawlik

 Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 8ae17a2..218bed3 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,3 +1,5 @@
+ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
+
 SUBDIRS = libgupnp-dlna tools tests data doc
 
 pkgconfig_DATA = gupnp-dlna-1.0.pc