vvp_reg.py: Allow to omit empty gold files

vvp_reg.py requires 4 gold files. One for each of stdout and stderr of both
iverilog and vvp. Most of these log files will be empty for most test
cases. This will result in a lot of empty files being added to the
repository.

If a gold file for a specific output stream can not be found assume that
the output stream is supposed to empty. This allows to omit the empty gold
files.

Also remove all the existing empty gold files.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

ivtest/run_ivl.py

@@ -90,8 +90,13 @@ def compare_files(log_path, gold_path):
 
     with open(log_path, 'rt') as fd:
         a = fd.readlines()
-    with open(gold_path, 'rt') as fd:
-        b = fd.readlines()
+
+    # Allow to omit empty gold files
+    if os.path.exists(gold_path):
+        with open(gold_path, 'rt') as fd:
+            b = fd.readlines()
+    else:
+        b = []
 
     flag = a == b
     if not flag: