Improve #include guard macros

Avoid using reserved identifiers such as `_DOHINT_H` (fixes #1989),
fix cases where the name doesn't match the filename, and make the naming
more consistent and less likely to collide with include guards in other
headers.

Examples/test-suite/refcount.h

@@ -1,5 +1,5 @@
-#ifndef TEST_SUITE_REFCOUNT_H__
-#define TEST_SUITE_REFCOUNT_H__
+#ifndef TEST_SUITE_REFCOUNT_H
+#define TEST_SUITE_REFCOUNT_H
 
 struct RCObjBase  {
   /*!
@@ -195,4 +195,4 @@ RCPtr<T>& RCPtr<T>::operator=(const RCPtr& rhs)
 
 
 
-#endif //TEST_SUITE_REFCOUNT_H__
+#endif // TEST_SUITE_REFCOUNT_H

Examples/test-suite/template_typedef_cplx2.h

@@ -1,5 +1,5 @@
-#ifndef ___typedef_import_h__
-#define ___typedef_import_h__
+#ifndef TEMPLATE_TYPEDEF_CPLX2_H
+#define TEMPLATE_TYPEDEF_CPLX2_H
 
 #ifdef SWIG
 %module template_typedef_cplx2;
@@ -174,4 +174,4 @@ namespace vfncs {
 
 #endif
 
-#endif //___template_typedef_h__
+#endif // TEMPLATE_TYPEDEF_CPLX2_H