Catch too-large allocations and emit an error message (#4505)

Catch too-large allocations and emit an error message (#4505)

This is a temporary measure until we fix the bug properly (which is
somewhat tricky, and we think might be easier in the new code
generator).

For now we get:

ghc-stage2: sorry! (unimplemented feature or known bug)
  (GHC version 7.1 for i386-unknown-linux):
        Trying to allocate more than 1040384 bytes.

See: http://hackage.haskell.org/trac/ghc/ticket/4550
Suggestion: read data from a file instead of having large static data
structures in the code.