https://issues.apache.org/jira/browse/AMQCPP-594

Remove forced stlport4 in configure, user can configure their build as
appropriate for their given env. 
diff --git a/activemq-cpp/configure.ac b/activemq-cpp/configure.ac
index 98f3bd4..07700bc 100644
--- a/activemq-cpp/configure.ac
+++ b/activemq-cpp/configure.ac
@@ -197,7 +197,7 @@
     if ! test "$GCC" = "yes"; then
        # Assuming Sun Compiler and adding in optimization
        # because autoconf can't seem to figure it out.
-       PLAT_CXXFLAGS="-mt -w -O5 -library=stlport4"
+       PLAT_CXXFLAGS="-mt -w -O5"
     fi
     ;;