Remove redundant `$!` and unused language pragma.

[markus1189]

Hi Michael :)

I found some suggestions from hlint and applied them:

• date-cache/System/Date/Cache.hs: remove redundant $!
• fast-logger/System/Log/FastLogger.hs: unused pragma BangPatterns

the redundant $! occurences where of the form:

somefunc = f $! (x,y)

which will not do anything because due to the tuple literal the argument to f already is in WHNF.

-- 24pullrequests

[snoyberg]

Pinging @kazu-yamamoto, I'd rather leave it to you to make a decision on these.

[kazu-yamamoto]

Merged. Thanks.