Build everything as C++ (#1176)

include/version.hpp

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef EXTERN_VERSION_H
+#define EXTERN_VERSION_H
+
+extern "C" {
+
+#define PACKAGE_VERSION_MAJOR 0
+#define PACKAGE_VERSION_MINOR 6
+#define PACKAGE_VERSION_PATCH 1
+
+char const *get_package_version_string(void);
+
+}
+
+#endif // EXTERN_VERSION_H