databases/postgresql-plv8js: disable C++ RTTI

Fixes
/usr/local/lib/postgresql/plv8-3.0.0.so: Undefined symbol
"_ZTIN2v811ArrayBuffer9AllocatorE"

Also enable V8 pointer compression, fixes
Embedder-vs-V8 build configuration mismatch. On embedder side pointer
compression is DISABLED while on V8 side it's ENABLED.

PR: 259262
Reported by: ryan@cybership.net
Submitted by: felix@palmen-it.de

Sponsored by: Postgres Professional