dev-lang/GHC: add missing patch

packages/dev-lang/GHC/files/GHC-8.8.1-no-alex.patch

@@ -0,0 +1,33 @@
+https://github.com/gentoo-haskell/gentoo-haskell/issues/959
+
+From 144abba394c6a23eb877fbde727111a5e75b9d47 Mon Sep 17 00:00:00 2001
+From: Ben Gamari <ben@smart-cactus.org>
+Date: Wed, 18 Sep 2019 23:50:20 -0400
+Subject: [PATCH] configure: Don't depend upon alex in source dist build
+
+This fixes #16860 by verifying that the generated sources don't already
+exist before asserting that the `alex` executable was found. This
+replicates the logic already used for `happy` in the case of `alex`.
+---
+ aclocal.m4 | 7 +++++--
+ 1 file changed, 5 insertions(+), 2 deletions(-)
+
+--- a/aclocal.m4
++++ b/aclocal.m4
+@@ -984,8 +984,11 @@ else
+ fi;
+ changequote([, ])dnl
+ ])
+-FP_COMPARE_VERSIONS([$fptools_cv_alex_version],[-lt],[3.1.7],
+-  [AC_MSG_ERROR([Alex version 3.1.7 or later is required to compile GHC.])])[]
++if test ! -f compiler/parser/Lexer.hs
++then
++    FP_COMPARE_VERSIONS([$fptools_cv_alex_version],[-lt],[3.1.7],
++      [AC_MSG_ERROR([Alex version 3.1.7 or later is required to compile GHC.])])[]
++fi
+ AlexVersion=$fptools_cv_alex_version;
+ AC_SUBST(AlexVersion)
+ ])
+-- 
+2.23.0
+