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.

Hide ICU C++ APIs from pg_locale.h

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