Fixed compilation error in Linux when the legacy configure is being used: multiple declaration of socklen_t. Also does similar things with os_sunos, os_darwinos, and os_rtems

git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@716 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/pjlib/include/pj/compat/os_rtems.h b/pjlib/include/pj/compat/os_rtems.h
index f764f9b..3f60656 100644
--- a/pjlib/include/pj/compat/os_rtems.h
+++ b/pjlib/include/pj/compat/os_rtems.h
@@ -128,6 +128,9 @@
  */
 #define PJ_THREAD_ALLOCATE_STACK    1
 
+/* RTEMS has socklen_t (does it? )*/
+#define PJ_HAS_SOCKLEN_T	    1
+