[9fans] power64 architecture v. fossil

[erik quanstrom]

amuzing bug 'o the day.

while 9c isn't in the standard distribution,
if one has OS=9* and does a mk clean in /sys/src/cmd/fossil,
you will remove 9.h since 9.h looks like a temporary name
for a command named "h" for the power64 architecture.

- erik