pg_dump: Reduce use of global variables

Most pg_dump.c global variables, which were passed down individually to
dumping routines, are now grouped as members of the new DumpOptions
struct, which is used as a local variable and passed down into routines
that need it.  This helps future development efforts; in particular it
is said to enable a mode in which a parallel pg_dump run can output
multiple streams, and have them restored in parallel.

Also take the opportunity to clean up the pg_dump header files somewhat,
to avoid circularity.

Author: Joachim Wieland, revised by Álvaro Herrera
Reviewed by Peter Eisentraut

src/bin/pg_dump/pg_backup_tar.c

@@ -27,12 +27,11 @@
  *
  *-------------------------------------------------------------------------
  */
+#include "postgres_fe.h"
 
-#include "pg_backup.h"
 #include "pg_backup_archiver.h"
 #include "pg_backup_tar.h"
 #include "pg_backup_utils.h"
-#include "parallel.h"
 #include "pgtar.h"
 
 #include <sys/stat.h>
@@ -48,7 +47,7 @@ static int	_WriteByte(ArchiveHandle *AH, const int i);
 static int	_ReadByte(ArchiveHandle *);
 static void _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len);
 static void _ReadBuf(ArchiveHandle *AH, void *buf, size_t len);
-static void _CloseArchive(ArchiveHandle *AH);
+static void _CloseArchive(ArchiveHandle *AH, DumpOptions *dopt);
 static void _PrintTocData(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt);
 static void _WriteExtraToc(ArchiveHandle *AH, TocEntry *te);
 static void _ReadExtraToc(ArchiveHandle *AH, TocEntry *te);
@@ -827,7 +826,7 @@ _ReadBuf(ArchiveHandle *AH, void *buf, size_t len)
 }
 
 static void
-_CloseArchive(ArchiveHandle *AH)
+_CloseArchive(ArchiveHandle *AH, DumpOptions *dopt)
 {
 	lclContext *ctx = (lclContext *) AH->formatData;
 	TAR_MEMBER *th;
@@ -850,7 +849,7 @@ _CloseArchive(ArchiveHandle *AH)
 		/*
 		 * Now send the data (tables & blobs)
 		 */
-		WriteDataChunks(AH, NULL);
+		WriteDataChunks(AH, dopt, NULL);
 
 		/*
 		 * Now this format wants to append a script which does a full restore