Explicitely use python2 for me_cleaner. Fixes issues in Arch which has python3 as default

build_coreboot.sh

@@ -624,9 +624,9 @@ else
 fi
 
 if [ $SKL -eq 0 ]; then
-    ./me_cleaner/me_cleaner.py -S build/coreboot.rom
+    python2 ./me_cleaner/me_cleaner.py -S build/coreboot.rom
 else
-    ./me_cleaner/me_cleaner.py -S -e "MFS" build/coreboot.rom
+    python2 ./me_cleaner/me_cleaner.py -S -e "MFS" build/coreboot.rom
 fi
     
 cp build/coreboot.rom "../$COREBOOT_FILENAME"