- Commit 3eb77eba5a, which moved the pending ops queue from md.c to
sync.c, introduced a duplicate, unused 'pendingOpsCxt'
variable. (I'm surprised none of the compilers or static analysis
tools have complained about that.)
- Commit c2fe139c20 moved the 'synchronize_seqscans' variable and
introduced an extern declaration in tableam.h, making the one in
guc_tables.c unnecessary.
- Commit 6f0cf87872 removed the 'pgstat_temp_directory' GUC, but
forgot to remove the corresponding global variable.
- Commit 1b4e729eaa removed the 'pg_krb_realm' GUC, and its global
variable, but forgot the declaration in auth.h.
Spotted all these by reading the code.