Corrected .vhd extensions for test_bench_files.

libraries/base/ss/hdllib.cfg

@@ -14,8 +14,8 @@ synth_files =
     src/vhdl/ss_parallel.vhd
 
 test_bench_files = 
-    tb/vhdl/tb_mmf_ss_parallel
-    tb/vhdl/tb_mmf_ss_reorder
-    tb/vhdl/tb_ss
-    tb/vhdl/tb_ss_wide
-    tb/vhdl/tb_tb_ss
+    tb/vhdl/tb_mmf_ss_parallel.vhd
+    tb/vhdl/tb_mmf_ss_reorder.vhd
+    tb/vhdl/tb_ss.vhd
+    tb/vhdl/tb_ss_wide.vhd
+    tb/vhdl/tb_tb_ss.vhd