pg_basebackup: Try to fix some failures on Windows.

Commit ffd5365 messed up the
mechanism that was being used to pass parameters to LogStreamerMain()
on Windows. It worked on Linux because only Windows was using threads.
Repair by moving the additional parameters added by that commit into
the 'logstreamer_param' struct.

Along the way, fix a compiler warning on builds without HAVE_LIBZ.

Discussion: http://postgr.es/m/CA+TgmoY5=AmWOtMj3v+cySP2rR=Bt6EGyF_joAq4CfczMddKtw@mail.gmail.com

Author: robertmhaas

src/backend/replication/basebackup_gzip.c

@@ -61,15 +61,14 @@ const bbsink_ops bbsink_gzip_ops = {
 bbsink *
 bbsink_gzip_new(bbsink *next, bc_specification *compress)
 {
-	int		compresslevel;
-
 #ifndef HAVE_LIBZ
 	ereport(ERROR,
 			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 			 errmsg("gzip compression is not supported by this build")));
 	return NULL;				/* keep compiler quiet */
 #else
 	bbsink_gzip *sink;
+	int		compresslevel;
 
 	Assert(next != NULL);
 

src/bin/pg_basebackup/pg_basebackup.c

@@ -541,12 +541,12 @@ typedef struct
 	char		xlog[MAXPGPATH];	/* directory or tarfile depending on mode */
 	char	   *sysidentifier;
 	int			timeline;
+	WalCompressionMethod	wal_compress_method;
+	int			wal_compress_level;
 } logstreamer_param;
 
 static int
-LogStreamerMain(logstreamer_param *param,
-				WalCompressionMethod wal_compress_method,
-				int wal_compress_level)
+LogStreamerMain(logstreamer_param *param)
 {
 	StreamCtl	stream;
 
@@ -575,8 +575,8 @@ LogStreamerMain(logstreamer_param *param,
 													stream.do_sync);
 	else
 		stream.walmethod = CreateWalTarMethod(param->xlog,
-											  wal_compress_method,
-											  wal_compress_level,
+											  param->wal_compress_method,
+											  param->wal_compress_level,
 											  stream.do_sync);
 
 	if (!ReceiveXlogStream(param->bgconn, &stream))
@@ -634,6 +634,8 @@ StartLogStreamer(char *startpos, uint32 timeline, char *sysidentifier,
 	param = pg_malloc0(sizeof(logstreamer_param));
 	param->timeline = timeline;
 	param->sysidentifier = sysidentifier;
+	param->wal_compress_method = wal_compress_method;
+	param->wal_compress_level = wal_compress_level;
 
 	/* Convert the starting position */
 	if (sscanf(startpos, "%X/%X", &hi, &lo) != 2)
@@ -724,7 +726,7 @@ StartLogStreamer(char *startpos, uint32 timeline, char *sysidentifier,
 		int			ret;
 
 		/* in child process */
-		ret = LogStreamerMain(param, wal_compress_method, wal_compress_level);
+		ret = LogStreamerMain(param);
 
 		/* temp debugging aid to analyze 019_replslot_limit failures */
 		if (verbose)