patch 9.0.0103: if running configure with cached results -lrt may be missing

Problem:    If running configure with cached results -lrt may be missing.
Solution:   Use two cache variables, one without and one with -lrt.
            (closes #10799)  Swap checks to avoid adding -lrt unnecessarily.
diff --git a/src/version.c b/src/version.c
index ce6caa5..9f6b194 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    103,
+/**/
     102,
 /**/
     101,