Primop support in the Interpreter.

Interpreter: Add limited support for direct primop evaluation.

This commit adds support for a number of primops directly
to the interpreter. This avoids the indirection of going
through the primop wrapper for those primops speeding interpretation
of optimized code up massively.

Code involving IntSet runs about 25% faster with optimized core and these
changes. For core without breakpoints it's even more pronouced and I
saw reductions in runtime by up to 50%.

Running GHC itself in the interpreter was sped up by ~15% through this
change.

Additionally this comment does a few other related changes:

testsuite:
* Run foundation test in ghci and ghci-opt ways to test these
primops.
* Vastly expand the foundation test to cover all basic primops
  by comparing result with the result of calling the wrapper.

Interpreter:
* When pushing arguments for interpreted primops extend each argument to
  at least word with when pushing. This avoids some issues with big
  endian. We can revisit this if it causes performance issues.
* Restructure the stack chunk check logic. There are now macros for
  read accesses which might cross stack chunk boundries and macros which
  omit the checks which are used when we statically know we access an
  address in the current stack chunk.