ahc: fix strict aliasing warnings

Submitted by Martin Kelly

Link to original bug (#769167)

Description

Created attachment 332119
0001-ahc-fix-strict-aliasing-warnings.patch

gcc strict aliasing can break code that performs type-punning, unless
said type punning uses unions. See:

http://www.cocoawithlove.com/2008/04/using-pointers-to-recast-in-c-is-bad.html

for more details about the UNION_CAST macro that I used.

Patch 332119, "0001-ahc-fix-strict-aliasing-warnings.patch":
0001-ahc-fix-strict-aliasing-warnings.patch