Getting rid of some more lseek() calls

[Thomas Munro]

Hello,

Continuing the work done in commits 0dc8ead4 and c24dcd0c, here are a
few more places where we could throw away some code by switching to
pg_pread() and pg_pwrite().

0001-Use-pg_pread-and-pg_pwrite-in-slru.c.patch
Description: Binary data

0002-Use-pg_pwrite-in-rewriteheap.c.patch

Description: Binary data


0003-Use-pg_pwrite-in-walreceiver.c.patch

Description: Binary data