Avoid possible crash within libsanitizer.

ci: Use -fsanitize=undefined,alignment,address in linux tasks

Add workaround to make ubsan and ps_status.c compatible

Don't try to translate NULL in GetConfigOptionByNum().

Don't call fwrite() with len == 0 when writing out relcache init file.

Remove uses of register due to incompatibility with C++17 and up

Hide ICU C++ APIs from pg_locale.h

ci: test headerscheck, cpluspluscheck as part of CompilerWarnings task.

Fix lock assertions in dshash.c.

pgstat: remove stats_temp_directory.

pgstat: consistent function comment formatting.

pgstat: store statistics in shared memory.

pgstat: stats collector references in comments.

pgstat: consistent function comment formatting.

Mark pg_stat_get_subscription_stats() strict.

Fix NULL input behaviour of pg_stat_get_replication_slot().