Also check for C++.

configure.ac

@@ -248,6 +248,7 @@ AC_PROG_CPP
 AC_C_INLINE
 AC_PROG_CPP
 AC_PROG_F77
+AC_PROG_CXX
 
 AC_PATH_PROG([CPP], [cpp], [], [/usr/bin:/lib:$PATH])
 AC_DEFINE_UNQUOTED([CPP],["$CPP"],["Command which runs the C preprecessor"])