Drop the AUTOINCREMENT PRIMARY KEYs from the mlinks and keys tables.

Drop the AUTOINCREMENT PRIMARY KEYs from the mlinks and keys tables.
They are completely unused, and i cannot imagine what they *could*
ever be used for; but apparently, they are expensive to generate.

Standard DB build time goes down by 10%, now at 1.9x of makewhatis.
Standard DB size goes down by 4%, now at 11x of makewhatis.
DB build time with -Q goes down by 15%, now at 0.28x of makewhatis.
DB size with -Q goes down by 3%, now at 3.35x of makewhatis.

Optimization found somewhere above the Southern Balochistan desert,
near the Iran-Pakistan border.  Committing from Melbourne, Victoria.