Add filtername to brush doors from HL:S

[SirYodaJedi]

This PR attempts to enable the filtername KV on func_door, func_door_rotating, and func_water, which is present in the SDK, but is ifdefed to only be compiled in HL:S+HLDMS. This PR modifies the relevant ifdefs to also apply to Mapbase, without enabling any code unrelated to the block filter.

The filtername KV indicates a filter to determine entities (other than players) that can block the door (could be useful for NPCs). It is actually present in the vanilla FGD entry for func_door, despite not working outside of HL:S. It should be moved to the Door baseclass. A modified FGD entry is as such:

	filtername(filterclass) : "Block Filter Name" : : "Filter to use to determine entities that can block the door."

This is flagged as a draft, because it needs to be tested further (and apparently doesn't compile).

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Does this PR close any issues?

• No.

PR Checklist

• My PR follows all guidelines in the CONTRIBUTING.md file
• My PR targets a develop branch OR targets another branch with a specific goal in mind

[Blixibon]

Just FYI, I think the only reason this doesn't compile is because it has incorrect #ifdef syntax:

#ifdef HL1_DLL || MAPBASE

Instead of using #ifdef, it should use #if defined(), like this:

#ifdef defined(HL1_DLL) || defined(MAPBASE)

[SirYodaJedi]

Changed to this, as per other examples in SDK.

#if defined(HL1_DLL) || defined(MAPBASE)

Wonder why it still compiled on Linux.

[Blixibon]

Changed to this, as per other examples in SDK.

#if defined(HL1_DLL) || defined(MAPBASE)

I didn't realize I typed #ifdef instead of #if in my corrected version... sorry, I had just woken up 🤦

Wonder why it still compiled on Linux.

The SP SDK codebase makes Windows treat all compile warnings as errors, but it does not do that for Linux. I don't know if that's by design, but Linux/GCC is generally a lot stricter than Windows/VC++, so it tends to have a lot more warnings on average. You could see that the warning appeared on Linux, but did not result in an error:

In file included from /home/runner/work/source-sdk-2013/source-sdk-2013/sp/src/game/server/../../game/shared/baseplayer_shared.cpp:32:
/home/runner/work/source-sdk-2013/source-sdk-2013/sp/src/game/server/doors.h:144:16: warning: extra tokens at end of #ifdef directive
  144 | #ifdef HL1_DLL || MAPBASE
      |                ^~

It's interesting that they ended up having opposite roles this time