parser: Allow Lm (MODIFIER LETTER) category in identifiers
Easy fix in the parser to stop regressions, due to Unicode 7.0 changing
the classification of some prior code points.
Signed-off-by: Austin Seipp <austin@well-typed.com>
Test Plan: tests/parser/should_compile/T10196.hs
Reviewers: hvr, austin, bgamari
Reviewed By: austin, bgamari
Subscribers: thomie, bgamari
Differential Revision: https://phabricator.haskell.org/D969
GHC Trac Issues: Trac #10196