mk_invlists: Use abbreviations for Line Break

Unicode UAX #14 gives rules for the Line Break property using the short
names for them.  Prior to this commit, we mostly used the full names for
the classes in this property.  This commit changes to use the short
names.  This makes it easier to compare the code here with the UAX text.
The abbreviations aren't always straight forward, so it was easy to go
astray.

Author: khwilliamson