msvidc32: Remove unused DllMain() function

[Dmitry Timoshkov]

"Francois Gouget" <fgouget at free.fr> wrote:

> msvideo1.c defines a DllMain() function but:
>   * it is not exported in the spec file
>   * it is not referenced in any way anywhere else
>   * the native dll does not export a DllMain function either

DllMain does not need to be exported to define an entry point of the DLL.
Moreover, DllMain of msvidc32 initializes MSVIDC32_hModule which is used
later on.

-- 
Dmitry.