More cleanups of the include files

- centralizing to simplify the -I's required to compile

src/include/storage/backendid.h

@@ -0,0 +1,32 @@
+/*-------------------------------------------------------------------------
+ *
+ * backendid.h--
+ *    POSTGRES backend id communication definitions
+ *
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ * $Id: backendid.h,v 1.1 1996/08/28 01:57:54 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef	BACKENDID_H
+#define BACKENDID_H
+
+/* ----------------
+ *	pulled out of sinval.h to temporarily reduce #include nesting.
+ *	-cim 8/17/90
+ * ----------------
+ */
+typedef int16	BackendId;	/* unique currently active backend identifier */
+
+#define InvalidBackendId	(-1)
+
+typedef int32	BackendTag;	/* unique backend identifier */
+
+#define InvalidBackendTag	(-1)
+
+extern BackendId	MyBackendId;	/* backend id of this backend */
+extern BackendTag	MyBackendTag;	/* backend tag of this backend */
+
+#endif /* BACKENDID_H */