ghc: Add patch to make ghc look for llvm 6

p/ghc/debian/changelog

+ghc (8.4.3-3) experimental; urgency=medium
+
+  * Switch configure.ac to search for llvm 6.0
+
+ -- Gianfranco Costamagna <locutusofborg@debian.org>  Thu, 19 Jul 2018 12:16:02 +0200
+
 ghc (8.4.3-2) experimental; urgency=medium
 
   [ Gianfranco Costamagna ]

p/ghc/debian/patches/series

@@ -7,3 +7,4 @@ x32-use-native-x86_64-insn.patch
 use-stage1-binaries-for-install.patch
 llvm-targets-Add-versioned-ARM-targets.patch
 bsymbolic-only-for-registerised.patch
+use-llvm-6.0.patch

p/ghc/debian/patches/use-llvm-6.0.patch

+Description: Use llvm 6.0 on arm*
+Author: Gianfranco Costamagna <locutusofborg@debian.org>
+Last-Update: 2018-07-19
+
+--- ghc-8.4.3.orig/configure.ac
++++ ghc-8.4.3/configure.ac
+@@ -638,7 +638,7 @@ AC_SUBST([LibtoolCmd])
+ # tools we are looking for. In the past, GHC supported a number of
+ # versions of LLVM simultaneously, but that stopped working around
+ # 3.5/3.6 release of LLVM.
+-LlvmVersion=5.0
++LlvmVersion=6.0
+ AC_SUBST([LlvmVersion])
+ sUPPORTED_LLVM_VERSION=$(echo \($LlvmVersion\) | sed 's/\./,/')
+ AC_DEFINE_UNQUOTED([sUPPORTED_LLVM_VERSION], ${sUPPORTED_LLVM_VERSION}, [The supported LLVM version number])