Prevent possible loss of committed transactions during crash

Due to insufficient interlocking between transaction commit and checkpointing, it was possible for transactions committed just before the most recent checkpoint to be lost, in whole or in part, following a database crash and restart. This is a serious bug that has existed since PostgreSQL 7.1.

Fix corner case for btree search in parallel with first root page split

Fix buffer overrun in to_ascii (Guido Notari)

Fix core dump in deadlock detection on machines where char is unsigned

Fix failure to respond to pg_ctl stop -m fast after Async_NotifyHandler runs

Repair memory leaks in pg_dump

Avoid conflict with system definition of isblank() function or macro