Use cross-platform sed syntax

https://stackoverflow.com/questions/1251999/how-can-i-replace-a-newline-n-using-sed?page=1&tab=votes#comment9175314_1252191

utils/script.sh

@@ -25,7 +25,7 @@ cut -f 1 -d ':' | \
 # Remove www
 # Only matches domains that start with www
 # Not examplewww.com
-sed ':a;N;$!ba;s/\nwww\./\n/g' | \
+sed -e ':a' -e 'N' -e '$!ba' -e 's/\nwww\./\n/g' | \
 # Sort and remove duplicates
 sort -u | \
 # Exclude Umbrella Top 1M. grep inverse match whole line

utils/umbrella-top-1m.sh

@@ -16,7 +16,7 @@ cut -f 2 -d ',' | \
 # Remove www
 # Only matches domains that start with www
 # Not examplewww.com
-sed ':a;N;$!ba;s/\nwww\./\n/g' | \
+sed -e ':a' -e 'N' -e '$!ba' -e 's/\nwww\./\n/g' | \
 # Remove duplicates
 sort -u > ../src/top-1m.txt