build: fix IoctlSocket FIONBIO check

[Tachi107]

HAVE_IOCTLSOCKET_CAMEL_FIONBIO should get defined if IoctlSocket with FIONBIO is available, but the current check uses the (lowercase) ioctlsocket function, resulting in the same check that is done for HAVE_IOCTLSOCKET_FIONBIO.

But... Does this make sense? This doesn't really check that ioctlsocket supports the FIONBIO mode, but it just makes sure that the code compiles; so in reality this just checks if FIONBIO is defined, since the ioctlsocket check is already made when setting HAVE_IOCTLSOCKET. But maybe I'm missing something, I'm not really familiar with the Win32 API (or Amiga, since this seems the only system that has a camelcase IoctlSocket function).

[jay]

This doesn't really check that ioctlsocket supports the FIONBIO mode

It looks like it checks by calling IoctlSocket with a socket of 0 in FIONBIO so it does check something... beats me if it actually works or not. Anyone that can target amiga want to check?

[bagder]

Seems correct based on the code. I cannot verify that it actually does right on such a target.

[Tachi107]

Me neither :/

[jay]

Looks right enough. Thanks