crystal-lang: move llvm 3.9 patch to stable

The llvm 3.9 patch was merged to crystal-lang master so is no longer
needed for the head spec.

Closes #6139.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>

Formula/crystal-lang.rb

@@ -1,10 +1,21 @@
 class CrystalLang < Formula
   desc "Fast and statically typed, compiled language with Ruby-like syntax"
   homepage "https://crystal-lang.org/"
-  url "https://github.com/crystal-lang/crystal/archive/0.19.4.tar.gz"
-  sha256 "e239afa449744e0381823531f6af66407ba1f4b78767bd67a9bb09d9fcc6b9e4"
-  head "https://github.com/crystal-lang/crystal.git"
   revision 1
+  head "https://github.com/crystal-lang/crystal.git"
+
+  stable do
+    url "https://github.com/crystal-lang/crystal/archive/0.19.4.tar.gz"
+    sha256 "e239afa449744e0381823531f6af66407ba1f4b78767bd67a9bb09d9fcc6b9e4"
+
+    # Remove for > 0.19.4
+    # changes already merged upstream to fix compilation with LLVM 3.9
+    # https://github.com/crystal-lang/crystal/pull/3439
+    patch do
+      url "https://github.com/crystal-lang/crystal/commit/13b11d7.patch"
+      sha256 "d981515791c48ae7fce0e906b0eec934fd622987a87f0614b3c91c71b0966b66"
+    end
+  end
 
   bottle do
     sha256 "b570dcde6496464362a19e2fb15379b7d1c1ad0f93bfd8bac9d587393912d887" => :sierra
@@ -12,12 +23,6 @@ class CrystalLang < Formula
     sha256 "8077a0a4a922112ec2438dbb99fc01931c14222a1c33a66218ad28d91036cab7" => :yosemite
   end
 
-  # changes from upstream to fix compilation with LLVM 3.9
-  patch do
-    url "https://github.com/crystal-lang/crystal/pull/3439.diff"
-    sha256 "ee55985315881461f1fd2fb7ccc36b547d5defb23a91b022c760d84abe328fd9"
-  end
-
   option "without-release", "Do not build the compiler in release mode"
   option "without-shards", "Do not include `shards` dependency manager"