Check/BenchX.template.hs : Remove un-needed #ifdef.
Common/.../StrictPrim.hs : Expose StrictPrim constructor etc.

* Exposure of StrictPrim contstructor is needed by a performance hack.
* Add bang patterns in a couple more places.
* Add #ifdefs to make it compile with ghc-7.9 (git HEAD).
Apply awesome New3.timesNatural performance hack from Amos Robinson.

The New3.timesNatural function was displaying some really odd performance
characteristics. Sometimes it would run 4 times slower than the other
timesNatural implementations and other times it would run 2 times faster.

It turned out that 'make clean' followed by 'make $benchmark' would
result in New3.timesNatural running 4 times slower than the others
while if the file New3/.../Natural.hs was touched and the benchmark
program rebuilt, it would run 2 times faster than the others.

This was raised as GHC performance bug here:

    https://ghc.haskell.org/trac/ghc/ticket/9646

Mentioned this to Amos Robinson and he looked at the output file from
GHC's simplifier stage and said:

   "I think it’s the eta expansion, and if we could force it to happen
   at the outermost level of innerloop it’d help."

and then came up with a variant of this hack.
bench-integer.hs : Tweak benchmark run params to improve quality of results.