configure.ac: don’t force struct-packing on Windows
configure.ac: don’t force struct-packing on Windows

This is a matter for the compiler configuration and user.

albbas/enchant,albbas/enchant,AbiWord/enchant,albbas/enchant,albbas/enchant,rrthomas/enchant,rrthomas/enchant,AbiWord/enchant,rrthomas/enchant,rrthomas/enchant,AbiWord/enchant,AbiWord/enchant