fix?(package): postgreact: ~stir the stupid shit till it works [3]

package/c/postgreact/postgreact.h

@@ -1,3 +1,6 @@
+#ifndef POSTGREACT_H
+#define POSTGREACT_H
+
 #include "postgres.h"
 
 #ifdef PG_MODULE_MAGIC
@@ -9,3 +12,5 @@ void _PG_fini(void);
 
 Datum hello(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(hello);
+
+#endif // POSTGREACT_H