Allow calling from RTEMS test harness.

src/libCom/test/epicsExceptionTest.cpp

@@ -101,7 +101,7 @@ void myThread::waitForCompletion ()
     }
 }
 
-void epicsExceptionTest ()
+extern "C" void epicsExceptionTest ()
 {
     myThread athread;
 

src/libCom/test/epicsExceptionTestMain.cpp

@@ -8,7 +8,7 @@
 * in file LICENSE that is included with this distribution. 
 \*************************************************************************/
 
-void epicsExceptionTest ();
+extern "C" void epicsExceptionTest ();
 
 int main ()
 {