Added a note on using Macports on Mac to install the APR dependencies.

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-cpp/trunk@783001 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/activemq-cpp/README.txt b/activemq-cpp/README.txt
index b6ea1ae..4606460 100644
--- a/activemq-cpp/README.txt
+++ b/activemq-cpp/README.txt
@@ -86,6 +86,12 @@
 APR-Util 1.2.x, this implies that you will need to build and install APR from
 the source download at Apache.
 
+On Mac you can use MacPorts to install a version of APR and APR-Util that
+works with ActiveMQ-CPP.  At the time of this writing the MacPorts versions
+were APR 1.3.3 and APR-Util 1.3.4 respectively.  See the MacPorts website for
+instructions on how to install the MacPorts utility and on using it to install
+the APR libraries.
+
 1.4 GNU Build System (for building on Unix/Linux/OS X)
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