fix latest gcc builds (#19)

Co-authored-by: Danny Parker <DannyParker0001@users.noreply.github.com>

engine/gl_matsysiface.cpp

@@ -972,7 +972,7 @@ void DebugDrawLightmapAtCrossHair()
 	IMaterial *pMaterial;
 	int lightmapPageSize[2];
 
-	if( s_CrossHairSurfID <= 0 )
+	if( s_CrossHairSurfID <= (SurfaceHandle_t)0 )
 	{
 		return;
 	}

game/client/clientmode_shared.cpp

@@ -1152,7 +1152,7 @@ void ClientModeShared::FireGameEvent( IGameEvent *event )
 			}
 		}
 
-		if ( team == 0 && GetLocalTeam() > 0 )
+		if ( team == 0 && GetLocalTeam() > (C_Team*)0 )
 		{
 			bValidTeam = false;
 		}

materialsystem/shaderapidx9/shaderdevicedx8.cpp

@@ -619,7 +619,7 @@ bool CShaderDeviceMgrDx8::ComputeCapsFromD3D( HardwareCaps_t *pCaps, int nAdapte
 		if ( pVendorID )
 		{
 			int nVendorID = V_atoi( pVendorID );	// use V_atoi for hex support
-			if ( pVendorID > 0 )
+			if ( pVendorID > (HardwareCaps_t*)0 )
 			{
 				ident.VendorId = nVendorID;
 			}

serverbrowser/CustomGames.cpp

@@ -211,7 +211,7 @@ bool CCustomGames::CheckTagFilter( gameserveritem_t &server )
 		V_SplitString( m_szTagFilter, ",", TagList );
 		for ( int i = 0; i < TagList.Count(); i++ )
 		{
-			if ( ( Q_strnistr( server.m_szGameTags, TagList[i], MAX_TAG_CHARACTERS ) > 0 ) == TagsExclude() )
+			if ( ( Q_strnistr( server.m_szGameTags, TagList[i], MAX_TAG_CHARACTERS ) > (const char*)0 ) == TagsExclude() )
 			{
 				bRetVal = false;
 				break;