Make sure mapsize changes take effect on Windows.
Revert "ITS#7772 Reduce spurious sub-page growth."

This reverts commit 75494c08b49c3ef77dce8a00f2bc44c83658c1a7,
which must await a fix to ITS#7771 (DUPSORT cursor tracking).
Note changes for LMDB 0.9.11
Bump version to 0.9.11