dsda: scale back MmapHeapSize

slaughter maps have gigantic savestates so they're not very tasable until we move from wbx to native. so no point in claiming complete support for them right away. okuplok launches, but might crash maybe

Author: vadosnaprimer

src/BizHawk.Emulation.Cores/Computers/Doom/DSDA.cs

@@ -123,7 +123,7 @@ public DSDA(CoreLoadParameters<DoomSettings, DoomSyncSettings> lp)
 				SealedHeapSizeKB = 4 * 1024,
 				InvisibleHeapSizeKB = totalWadSizeKb + 4 * 1024, // Make sure there's enough space for the wads
 				PlainHeapSizeKB = 4 * 1024,
-				MmapHeapSizeKB = 1024 * 1024 * 2, // Allow the game to malloc quite a lot of objects to support those big wads
+				MmapHeapSizeKB = 1024 * 1024, // Allow the game to malloc quite a lot of objects to support those big wads
 				SkipCoreConsistencyCheck = lp.Comm.CorePreferences.HasFlag(CoreComm.CorePreferencesFlags.WaterboxCoreConsistencyCheck),
 				SkipMemoryConsistencyCheck = lp.Comm.CorePreferences.HasFlag(CoreComm.CorePreferencesFlags.WaterboxMemoryConsistencyCheck),
 			});