flang 19.1.1

Also:
- remove the `zstd` and `zlib` dependencies since there's no actual
  linkage
- reduce the scope of the `llvm` method to a variable in `install`

Formula/f/flang.rb

@@ -1,8 +1,8 @@
 class Flang < Formula
   desc "LLVM Fortran Frontend"
   homepage "https://flang.llvm.org/"
-  url "https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.0/llvm-project-19.1.0.src.tar.xz"
-  sha256 "5042522b49945bc560ff9206f25fb87980a9b89b914193ca00d961511ff0673c"
+  url "https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.1/llvm-project-19.1.1.src.tar.xz"
+  sha256 "d40e933e2a208ee142898f85d886423a217e991abbcd42dd8211f507c93e1266"
   # The LLVM Project is under the Apache License v2.0 with LLVM Exceptions
   license "Apache-2.0" => { with: "LLVM-exception" }
   head "https://github.com/llvm/llvm-project.git", branch: "main"
@@ -23,17 +23,12 @@ class Flang < Formula
 
   depends_on "cmake" => :build
   depends_on "llvm"
-  depends_on "zstd"
-  uses_from_macos "zlib"
-
-  def llvm
-    Formula["llvm"]
-  end
 
   # Building with GCC fails at linking with an obscure error.
   fails_with :gcc
 
   def install
+    llvm = Formula["llvm"]
     # NOTE: Setting `BUILD_SHARED_LIBRARIES=ON` causes the just-built flang to throw ICE.
     args = %W[
       -DCLANG_DIR=#{llvm.opt_lib}/cmake/clang