Make testsuite code C++ clean again.

[Ralf Wildenhues]

Applied to master as obvious.

Cheers,
Ralf

    Make testsuite code C++ clean again.
    
    * tests/resident.at (resident modules): Fix for C++.

diff --git a/tests/resident.at b/tests/resident.at
index 8667ca7..c16a72a 100644
--- a/tests/resident.at
+++ b/tests/resident.at
@@ -59,7 +59,7 @@ main (int argc, char* argv[])
        {
          int (*pf) (void);
          printf ("plugin opened successfully!\n");
-         pf = lt_dlsym (plugin_handle, "setup_plugin");
+         pf = (int (*) (void)) lt_dlsym (plugin_handle, "setup_plugin");
          if (pf)
            pf ();
          else
@@ -100,6 +100,7 @@ main (int argc, char* argv[])
 
 AT_DATA([plugin.c],
 [[#include <stdlib.h>
+#include <stdio.h>
 
 void
 bye (void)
@@ -107,6 +108,9 @@ bye (void)
   puts ("called from atexit handler");
 }
 
+#ifdef __cplusplus
+extern "C"
+#endif
 int
 setup_plugin (void)
 {