Enabled the REDISTRIBUTION option in the Makefile for sky130A.
Corrected the convert_spectre.py to ignore .scs files, which have
no SPICE equivalent.
diff --git a/common/convert_spectre.py b/common/convert_spectre.py
index e83cce0..6c3655c 100755
--- a/common/convert_spectre.py
+++ b/common/convert_spectre.py
@@ -499,6 +499,10 @@
             if fileext == '.v' or fileext == '.va':
                 continue
 
+            # .scs files are purely spectre and meaningless to SPICE, so ignore them.
+            if fileext == '.scs':
+                continue
+
             froot = os.path.split(filename)[1]
             convert_file(filename, spicepath + '/' + froot)