tests/tdef: rename the binaries to end with '_test'

It's the usual naming for unit test binaries.  Without the '_test' endig,
the tdef_vty_test_{config_root,config_subnode,dynamic} binaries do not
match the 'tests/*/*_test' pattern and appear as untracked files in git.

Change-Id: I828fa45132e11a41c527d4b25df850c19871cb75
diff --git a/src/tdef.c b/src/tdef.c
index 9890f95..75b884a 100644
--- a/src/tdef.c
+++ b/src/tdef.c
@@ -52,18 +52,18 @@
  * By keeping separate osmo_tdef arrays, several groups of timers can be kept
  * separately. The VTY tests in tests/tdef/ showcase different schemes:
  *
- * - \ref tests/vty/tdef_vty_test_config_root.c:
+ * - \ref tests/vty/tdef_vty_config_root_test.c:
  *   Keep several timer definitions in separately named groups: showcase the
  *   osmo_tdef_vty_groups*() API. Each timer group exists exactly once.
  *
- * - \ref tests/vty/tdef_vty_test_config_subnode.c:
+ * - \ref tests/vty/tdef_vty_config_subnode_test.c:
  *   Keep a single list of timers without separate grouping.
  *   Put this list on a specific subnode below the CONFIG_NODE.
  *   There could be several separate subnodes with timers like this, i.e.
  *   continuing from this example, sets of timers could be separated by placing
  *   timers in specific config subnodes instead of using the global group name.
  *
- * - \ref tests/vty/tdef_vty_test_dynamic.c:
+ * - \ref tests/vty/tdef_vty_dynamic_test.c:
  *   Dynamically allocate timer definitions per each new created object.
  *   Thus there can be an arbitrary number of independent timer definitions, one
  *   per allocated object.
diff --git a/src/vty/tdef_vty.c b/src/vty/tdef_vty.c
index 09459f1..bd209ae 100644
--- a/src/vty/tdef_vty.c
+++ b/src/vty/tdef_vty.c
@@ -242,7 +242,7 @@
 
 /*! Write current timer configuration arguments to the vty. Skip all entries that reflect their default value.
  * The passed prefix string must contain both necessary indent and the VTY command the specific implementation is using.
- * See tdef_vty_test_config_subnode.c and tdef_vty_test_dynamic.c for examples.
+ * See tdef_vty_config_subnode_test.c and tdef_vty_dynamic_test.c for examples.
  * \param[in] vty  VTY context.
  * \param[in] tdefs  Array of timers to print, ended with a fully zero-initialized entry.
  * \param[in] prefix_fmt  Arbitrary string to start each line with, with variable printf like arguments.