mpi, spectrum: Add missing header guards to example files

src/mpi/examples/mpi-test-fixtures.h

@@ -17,6 +17,9 @@
  * Author: Steven Smith <smith84@llnl.gov>
  */
 
+#ifndef MPI_TEST_FIXTURES_H
+#define MPI_TEST_FIXTURES_H
+
 #include <iomanip>
 #include <ios>
 #include <sstream>
@@ -156,3 +159,5 @@ class SinkTracer
 };
 
 } // namespace ns3
+
+#endif // MPI_TEST_FIXTURES_H

src/spectrum/test/spectrum-test.h

@@ -19,6 +19,9 @@
  * part of the code copied from test.h
  */
 
+#ifndef SPECTRUM_TEST_H
+#define SPECTRUM_TEST_H
+
 #include <ns3/spectrum-value.h>
 #include <ns3/test.h>
 
@@ -155,3 +158,5 @@
                               (__LINE__));                                                         \
         }                                                                                          \
     } while (false);
+
+#endif // SPECTRUM_TEST_H