Properly close files after read file failure to prevent potential

resource leak.  Of course, any such failure aborts pg_upgrade, but might
as well be clean about it.

Per patch from Grzegorz Ja?kiewicz.

contrib/pg_upgrade/file.c

@@ -74,7 +74,10 @@ copyAndUpdateFile(migratorContext *ctx, pageCnvCtx *pageConverter,
 				return "can't open source file";
 
 			if ((dstfd = open(dst, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR)) < 0)
+			{
+				fclose(src_fd);
 				return "can't create destination file";
+			}
 
 			while ((bytesRead = read(src_fd, buf, BLCKSZ)) == BLCKSZ)
 			{

contrib/pg_upgrade/page.c

@@ -103,7 +103,10 @@ getPageVersion(migratorContext *ctx, uint16 *version, const char *pathName)
 		return "can't open relation";
 
 	if ((bytesRead = read(relfd, &page, sizeof(page))) != sizeof(page))
+	{
+		close(relfd);
 		return "can't read page header";
+	}
 
 	*version = PageGetPageLayoutVersion(&page);