HDMI (TMDS) output with Digilent Atlys - examples do not compile with ISE 14.7
Welcome to the world of Xilinx :)

The problem is known, and I don't think they maintain this app very actively and if you search for the Answer Record mentioned in the error list, you will see that it requires some changes in the example code to make it compile with newer versions of ISE.

You can find the solution to your problem at:

Discussion about the problem with Digilent/Xilinx Example design at Xilinx forum  

You need to modify the vtc_demo.v to:

// Original code, doesn't work on ISE &gt;= 14.6
//  BUFIO2 #(.DIVIDE_BYPASS("FALSE"), .DIVIDE(2))
//  sysclk_div (.DIVCLK(clk50m), .IOCLK(), .SERDESSTROBE(), .I(sysclk));

  wire clkfb;

   DCM_SP #(
      .CLKDV_DIVIDE(2.0),
      .CLKFX_DIVIDE(1),
      .CLKFX_MULTIPLY(4),
      .CLKIN_DIVIDE_BY_2("TRUE"),
      .CLKIN_PERIOD(10.0),       
      .CLKOUT_PHASE_SHIFT("NONE"),
      .CLK_FEEDBACK("1X"),        
      .DESKEW_ADJUST("SYSTEM_SYNCHRONOUS"),
      .DFS_FREQUENCY_MODE("LOW"),         
      .DLL_FREQUENCY_MODE("LOW"),         
      .DSS_MODE("NONE"),                  
      .DUTY_CYCLE_CORRECTION("TRUE"),     
      .FACTORY_JF(16'hc080),              
      .PHASE_SHIFT(0),                    
      .STARTUP_WAIT("FALSE")              
   )
   DCM_SP_inst (
      .CLK0(clk50m),
      .CLK180(),    
      .CLK270(),    
      .CLK2X(),     
      .CLK2X180(),  
      .CLK90(),     
      .CLKDV(),     
      .CLKFX(),     
      .CLKFX180(),  
      .LOCKED(),    
      .PSDONE(),    
      .STATUS(),    
      .CLKFB(clkfb),
      .CLKIN(sysclk),
      .DSSEN(1'b0),  
      .PSCLK(1'b0),  
      .PSEN(1'b0),   
      .PSINCDEC(1'b0),
      .RST(1'b0)      
   );

   BUFIO2FB #( .DIVIDE_BYPASS("TRUE") )
   BUFIO2FB_inst ( .O(clkfb), .I(clk50m) );