Tweak _F_AWK settings
Tweak _F_AWK settings

f now works with mawk, though mawk performs the slowest out of all the
implementations. The preference list is ordered by the speed of running
plain `f` (listing all the entries).

Neki/fasd,dankilman/fasd,allcatsarebeautiful/fasd,alphapapa/fasd,Vifon/fasd,clvv/fasd