Fix missing abort checks in pg_backup_directory.c.

Parallel restore from directory format failed to respond to control-C
in a timely manner, because there were no checkAborting() calls in the
code path that reads data from a file and sends it to the backend.
If any worker was in the midst of restoring data for a large table,
you'd just have to wait.

This fix doesn't do anything for the problem of aborting a long-running
server-side command, but at least it fixes things for data transfers.

Back-patch to 9.3 where parallel restore was introduced.

src/bin/pg_dump/pg_backup_directory.c

@@ -406,7 +406,12 @@ _PrintFileData(ArchiveHandle *AH, char *filename)
 	buflen = ZLIB_OUT_SIZE;
 
 	while ((cnt = cfread(buf, buflen, cfp)))
+	{
+		/* Are we aborting? */
+		checkAborting(AH);
+
 		ahwrite(buf, 1, cnt, AH);
+	}
 
 	free(buf);
 	if (cfclose(cfp) !=0)
@@ -543,6 +548,9 @@ _ReadBuf(ArchiveHandle *AH, void *buf, size_t len)
 {
 	lclContext *ctx = (lclContext *) AH->formatData;
 
+	/* Are we aborting? */
+	checkAborting(AH);
+
 	/*
 	 * If there was an I/O error, we already exited in cfread(), so here we
 	 * exit on short reads.