Take steps to avoid misestimating range query costs based on STAT4 data
due to the roundoff error of converting from integers to LogEst and back
to integers.
Change the 0x800 bit of SQLITE_TESTCTRL_OPTIMIZATIONS so that it disables
the loading of STAT3 and STAT4 content, not just the using of that content.
Change the internal name of that bit to SQLITE_Stat34.
Disable the use of strchrnul() unless specifically enabled by compile-time
options.
Implement sqlite3_create_collation() by invoking 
sqlite3_create_collation_v2() with a NULL destructor argument.  This saves
a little space.