Foreign pointer declaration produces helper function without type signature, producing warning with -Wall

[ian-ross]

Bug imported from C2HS Trac

Trac ticket created: 2012-07-04T00:07:26-0700

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When given a pointer declaration for a foreign pointer, such as:

{# pointer *foo as ^ foreign newtype #}

c2hs produces a helper function withFoo, without a type signature. This causes GHC with -Wall to produce a warning message, "Warning: Top-level binding with no type signature".