Adjust largeobject_1.source per buildfarm.

Looks like the correct size of DOS-ified tenk.data is 680800 not 680801.
(I got the latter from a version of unix2dos that appends a trailing ^Z,
which evidently is not git's practice.)

src/test/regress/output/largeobject_1.source

@@ -226,7 +226,7 @@ UPDATE lotest_stash_values SET fd=lo_open(loid, CAST(x'20000' | x'40000' AS inte
 SELECT lo_lseek(fd, 0, 2) FROM lotest_stash_values;
  lo_lseek 
 ----------
-   680801
+   680800
 (1 row)
 
 -- with the default BLKSZ, LOBLKSZ = 2048, so this positions us for a block