Update extensions list for GHC-8.12

[phadej]

There are no changes in GHC HEAD yet.

[monoidal]

Currently, this includes LinearTypes and QualifiedDo; soon, also LexicalNegation.

[phadej]

Yes, I'm waiting for GHC-8.12-alpha1 until I proceed with this and other GHC-8.12 related bookkeeping issues.

[phadej]

% diff -u ext-8.10.txt ext-8.12.txt                                         
--- ext-8.10.txt	2020-07-07 14:16:47.762769381 +0300
+++ ext-8.12.txt	2020-07-07 14:16:43.342823211 +0300
@@ -57,7 +57,9 @@
 JavaScriptFFI
 KindSignatures
 LambdaCase
+LexicalNegation
 LiberalTypeSynonyms
+LinearTypes
 MagicHash
 MonadComprehensions
 MonadFailDesugaring
@@ -126,7 +128,9 @@
 NoJavaScriptFFI
 NoKindSignatures
 NoLambdaCase
+NoLexicalNegation
 NoLiberalTypeSynonyms
+NoLinearTypes
 NoMagicHash
 NoMonadComprehensions
 NoMonadFailDesugaring
@@ -158,6 +162,7 @@
 NoPolyKinds
 NoPolymorphicComponents
 NoPostfixOperators
+NoQualifiedDo
 NoQuantifiedConstraints
 NoQuasiQuotes
 NoRank2Types
@@ -213,6 +218,7 @@
 PolyKinds
 PolymorphicComponents
 PostfixOperators
+QualifiedDo
 QuantifiedConstraints
 QuasiQuotes
 Rank2Types

[phadej]

.. extension:: LexicalNegation
    :shortdesc: Use whitespace to determine whether the minus sign stands for
                negation or subtraction.

.. extension:: QualifiedDo
    :shortdesc: Enable qualified do-notation desugaring.

.. extension:: LinearTypes
    :shortdesc: Enable linear types.