Post release cleanup 6.3.8

…fu-snapshot-record-version

Merge 6.3 into master

…hed-data-ratio-knob

Remove deprecated UNFLUSHED_DATA_RATIO knob

Linking lpthread before libcrypto seems to have been causing an issue
since the crypto library (used in OpenSSL?) needs threading. Swapping
the order should fix the issue.

This is a (probably temporary?) fix to actually fix the compilation
issue with the added unit tests when compiling with gcc. The issue seems
to be that lpthread is getting linked before another library which
requires it, so linking fails. Linking pthread instead of lpthread fixes
the issue, but this may have an effect on other binaries in the system
as well.

…fu-snapshot-record-version

…ard-to-trace assertion

…imulation and running tests