Clarify when forcing the moves loop

In some cases we want to go direcly to the moves loop
without checking for early return. The patch make this
logic more clear and consistent.

Tested for no regression, passed STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 25282 W: 5136 L: 5022 D: 15124

and LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 72007 W: 12133 L: 12095 D: 47779

bench: 9316798
Assorted nitpicking code-style

No functional change.
Retire 'os' flag from Makefile

Appears to be unused

No functional change

Resolves #147
Fix profile build for syzygy

Touch source files under syzygy directory to force recompilation
after collecting profile data.

No functional change

Resolves #149
Try some instant moves.  Inspired by watching Gull play on TCEC.
adjust slow mover
Make insta move more conservative.  Revert slow mover to 80 as in master.
Try a tuning suggested by lp.
Bump time factor to .78 since .75 was about a 2 elo improvement over .71