Free write mutex earlier in txn_reset0
Must do dlist_free before releasing Wmutex
Don't use -fPIC for static lib
ITS#7952 .gitignore mdb_dump/load
ITS#7953 .gitignore *.lo
ITS#7955, #7671 fix MDB_PREV_DUP
ITS#7956 fix compact of empty env
ITS#7841 trivial cleanup

TRIVIA - lmdb: clean testdb-dir while "make test".
ITS#7959 Check fstat return value

Signed-off-by: Jean-Christophe DUBOIS <jcd@tribudubois.net>
ITS#7961 fix txn init

More fallout from 4d02c741b120786df1b87ee9ed49c1d3f9bc7522
ITS#7959 fix prev commit

fstat returns -1, not an errno. Move code into its own function
for reuse.
ITS#7961,#7987 Re-fix txn init.

More fallout from 4d02c741b120786df1b87ee9ed49c1d3f9bc7522:
Don't modify another thread's write txn. Reinit me_txn0 fully.
Simplify recent changes a bit.
Fix comments
mdb_strerror: Silence warning @ Windows
Fix WIN32 -> _WIN32
ITS#7987 fix excessive space for single write txn
Clarify mdb_dbi_open doc

The concurrency restriction is on threads within a single process.
Multiple processes can use mdb_dbi_open without affecting each other.
make clean: remove *.lo
Fix MDB_APPEND doc

We actually compare the new key against the last key, to prevent
corruption.