Introduced in 36963b6d.

To reduce the number of casts required and avoid a scan-build warning.

If the length of wszApplicationName exceeds 1024, it will cause an error
when writing to the subsequent stack space after exceeding the wcmd space,
Wcmd needs to be modified to dynamic allocation.
Signed-off-by: Jiajin Cui <cuijiajin@uniontech.com>

4.18+ Linux kernels remove support for IPX but keep SOL_IPX defined, which
causes compilation errors as wine unconditionally uses IPX structures if
this is the case. Instead check for IPX_MTU to determine IPX support as it is
defined within the ipx.h header itself.

And do some mandatory cleanup while at it.