Correct Env_ warning

1.12 created a warning message that is just annoying during builds. This fixes it and corrects MergeHelper::FilterMerge() to match PR Facebook accepted.

Disable all histogram and stop_watch usage

1. not all histograms will disable in this version 5.18. That creates a performance degradation if user supplies a statistics object.

2. the stop_watch object used in merge_helper is always calling the clock, even with statistics disabled.

Both changes are hacked into the code. The first will be fixed properly when we upgrade to rocksdb 6.x. The second requires a PR to facebook which I will create shortly.

removing toolchain

Merge pull request #20 from stardog-union/build/removing_toolchain

removing toolchain

Add SetBufferSize() to WriteBufferManager for our MemoryBudget

stardog-develop-1.10

make overall buffer size dynamic within WriteBufferManager (#19)

Fix compile error

tweaked to fix compile error

rocksdb::EncryptedEnvV2::SetKeys() now public

Stardog server is now capable of dynamically updating encryption keys. Previously the SetKeys() function was a protected function since it was not thread safe. Work done for Facebook made the function thread safe. So now making function public for the benefit of Stardog.

Update encryption code with changes / fixes from Facebook PR

stardog-develop-1.7 contains changes and fixes that were made due to suggestions from Facebook and bugs found by Facebook's CI. The changes are all related to encryption.

Update encryption for performance and Facebook requirements

Facebook made several design recommendations. Those recommendations are part of this release. The encryption format is INCOMPATIBLE with the previous code. Stardog made an explicit decision to not support an upgrade path since this and the prior encryption release are "feature preview" quality.

Fix Windows build

Encryption check-in did not fully disable certain parts of library_loader. Windows therefore failed since we are not building encryption there.

Raise default skip list height from 12 to 17

Skip lists are used to sort incoming data before writing to level-0 .sst file. The height of a skip list implies the number of objects held in the list. Original paper says height represents the power of 2 that exceeds expected number of objects.