nightly update

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@57816 65644016-39b1-43b1-bf79-96bc8fe82c15
Cleanup:
- removed never used bcb_checkpoint and BDB_checkpoint
- removed conditional compilation for CACHE_WRITER as it is already ruled by flag BCB_cache_writer at almost all places
- added necessary checks for BCB_cache_writer when it was missed


git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@57819 65644016-39b1-43b1-bf79-96bc8fe82c15