FT-594 add fractal tree version 24 (tokudb 7.0.1) and version 27 (tokudb 7.5.0) stress data directories
FT-594 add fractal tree version 26 stress data directories
Merge branch 'releases/tokumx-2.0'
Merge branch 'bugs/599'
fixed cmake warnings for 3.0.0
disabled keyrange until we fix it
optimized test_keylen_diff so it's faster under valgrind

also widened one valgrind suppression to also catch something we
initialize in the assert layer
fixed some helgrind warnings in ydb/helgrind_test_groupcommit_count.tdb
moved to generator expressions for cmake debug flags
use TOKU_ macros to handle !USE_VALGRIND
fixed some valgrind sanity tests
fixed cmake policy CMP0022:

either use all-plain or all-keyword style of target_link_libraries