Fix C++ wrap tests by cincluding the *.cpp source

tests/wrappers/cpp_overload_wrapper_lib.h

-
+#ifndef CPP_OVERLOAD_WRAPPER_LIB_H
+#define CPP_OVERLOAD_WRAPPER_LIB_H
 void voidfunc(void);
 
 double doublefunc (double a, double b, double c);
@@ -20,3 +21,4 @@ public:
 };
 
 double transmogrify_from_cpp (DoubleKeeper const *obj, double value);
+#endif

tests/wrappers/cpp_overload_wrapper_lib.pxd

-
+cdef extern from "cpp_overload_wrapper_lib.cpp":
+    pass
 cdef extern from "cpp_overload_wrapper_lib.h":
     void voidfunc()
     double doublefunc(double a, double b, double c)

tests/wrappers/cppwrap_lib.h

-
+#ifndef CPPWRAP_LIB_H
+#define CPPWRAP_LIB_H
 void voidfunc(void);
 
 double doublefunc (double a, double b, double c);
@@ -18,3 +19,4 @@ public:
 };
 
 double transmogrify_from_cpp (DoubleKeeper const *obj, double value);
+#endif

tests/wrappers/cppwrap_lib.pxd

-
+cdef extern from "cppwrap_lib.cpp":
+    pass
 cdef extern from "cppwrap_lib.h":
     void voidfunc()
     double doublefunc(double a, double b, double c)