pgsql: Remove useless lstat() call in pg_rewind.

Remove useless lstat() call in pg_rewind.

This is duplicative of an lstat that was just done by the calling
function (traverse_datadir), besides which we weren't really doing
anything with the results. There's not much point in checking to
see if someone removed the file since the previous lstat, since the
FILE_ACTION_REMOVE code would have to deal with missing-file cases
anyway. Moreover, the "exists = false" assignment was a dead store;
nothing was done with that value later.

A syscall saved is a syscall earned, so back-patch to 9.5
where this code was introduced.

Discussion: https://postgr.es/m/1221796.1599329320@sss.pgh.pa.us

Branch
------
REL_11_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/75e44b471c511bc2aec0e869ab0d23d249890734

Modified Files
--------------
src/bin/pg_rewind/filemap.c | 12 ------------
1 file changed, 12 deletions(-)