[aravis] build: make it work with old autotools.

[Emmanuel Pacaud <emmanuel src gnome org>]

commit 8e3503893132e886cad6ca8525ec7623af4a97ab
Author: Emmanuel Pacaud <emmanuel gnome org>
Date:   Mon Apr 26 15:30:44 2010 +0200

    build: make it work with old autotools.

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index a95c588..2556541 100644
--- a/configure.ac
+++ b/configure.ac
@@ -45,7 +45,7 @@ with_cairo=no
 if test "x$enable_cairo" = "xyes"; then
 	PKG_CHECK_MODULES([CAIRO],   [cairo >= 1.2],
 			  [AC_DEFINE([ARAVIS_WITH_CAIRO], [1], [Cairo support])
-			  ARAVIS_REQUIRES+=" [cairo >= 1.2]"
+			  ARAVIS_REQUIRES="${ARAVIS_REQUIRES} [cairo >= 1.2]"
 			  with_cairo=yes],
 			  [echo -n])
 fi
@@ -55,7 +55,7 @@ with_gstreamer=no
 if test "x$enable_gstreamer" = "xyes"; then
 	PKG_CHECK_MODULES([GSTREAMER],   [gstreamer-base-0.10 >= 0.10],
 			  [AC_DEFINE([ARAVIS_WITH_GSTREAMER], [1], [Cairo support])
-			  ARAVIS_REQUIRES+=" [gstreamer-base-0.10 >= 0.10]"
+			  ARAVIS_REQUIRES="${ARAVIS_REQUIRES} [gstreamer-base-0.10 >= 0.10]"
 			  with_gstreamer=yes],
 			  [echo -n])
 fi