dev-db/postgresql: Spinlocks, pushd, and man

dev-db/postgresql: Spinlocks, pushd, and man

All versions now generate slotted man pages instead of using
symlinks. This is cleaner, and won’t result in broken links. You can
now run ‘man psql96’ (or similar) and actually get the man page for
psql, version 9.6.x.

10_beta2 and 9999 now dies if it can’t pushd into the directory it
needs to be in when generating the man pages.

Re-disabled spinlocks for versions 9.5 and after. Somehow this got
excluded from the 9.6 release.

Package-Manager: Portage-2.3.6, Repoman-2.3.1