[cffLib] replace print with logger (but keep debug messages off)
[cffLib] replace print with logger (but keep debug messages off)

All these debug messages were disabled, and I don't wish to re-enable them
while running TTX in verbose mode. So here I use a custom level less than
logging.DEBUGm to make sure they will be muted even when the logger's level
is equal to logging.DEBUG.

googlefonts/fonttools,fonttools/fonttools