WIP: ptx: attempt to fix foldAllCore

Missing the ability to insert phi nodes directly. Eep!!
table: can't make weak pointers to values in the C heap

Attach the pointer to the ArrayData (which lives in the GHC heap), rather than trying to pin this on the raw Addr#.
sort extensions list
native/map: awful, awful fix... >_<
Revert "mark loop combinator modules as deprecated"

This reverts commit 228504ccb1b3c0e1204ca32b6d3fab23af6b2610.
Revert: use monadic-style ptx map kernel
Revert: use monadic-style ptx transform kernel
Revert: use monadic-style ptx generate kernel
Revert: use monadic-style ptx fold kernels
ptx/fold: tidy handling of seed elements
ptx: no longer using llvm-quote
ptx: cabal wibbles
table: handle the possibility of collisions

Since we are using the host array pointer as the memory table key, there is a possibly that this can be re-used once the host array is dead but before the remote array is finalised.

See note: [Host arrays as memory table keys]
add scanr1 skeleton
fix scan(l/r)1 skeletons
add scanl skeletons
add scanr skeleton
fix types of stencil operations
first go on stencil
adjust to change in llvm-general

LocalReference and GlobalReference now have an additional type