ci(release): build a universal binary on macOS

After some tweaks to our dep builds, we can now build a universal binary
for macOS by using `CMAKE_OSX_ARCHITECTURES`. So, let's do that. This
requires a number of additional changes:

1. We need to build on macOS 11, since earlier versions do not support
   building universal (M1 + Intel) binaries.
2. We need to provision a universal `libintl`. The linker will look for
   an ARM64 version of this library when linking the `nvim` binary.

While we're here:
1. Link statically to `libintl`. This allows to to avoid having to do
   any install name rewriting or codesigning to package Neovim.
2. Bump the `MACOSX_DEPLOYMENT_TARGET` to `11`. We're already using a
   `libintl` built by Homebrew (through the pre-installed version of
   `gettext`), and that is built for macOS 11.

In order to ensure we link to `libintl.a` instead of `libintl.dylib`, we
have to make sure that CMake can't find the latter. This ideally should
be a matter of doing `brew unlink gettext`. However, CMake is too adept
at finding things that Homebrew has installed (even when not linked), so
we have to do a bit more than that. This appears in the additional step
ensuring static linkage to `libintl`.

We end up breaking some Homebrew-installed software in the process, and
some of these software is called during our build (e.g. curl, git,
wget). To avoid any adverse effects, let's just uninstall them.

2 files changed, 27 insertions, 18 deletions

diff --git a/.github/workflows/notes.md b/.github/workflows/notes.md
index 3bd6c739a5..86f9e8e618 100644
--- a/.github/workflows/notes.md
+++ b/.github/workflows/notes.md
@@ -22,7 +22,7 @@ ${NVIM_VERSION}
 
 1. Download **nvim-macos.tar.gz**
 2. Extract: `tar xzvf nvim-macos.tar.gz`
-3. Run `./nvim-osx64/bin/nvim`
+3. Run `./nvim-macos/bin/nvim`
 
 ### Linux (x64)
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index aad76d0979..1c6e62abbb 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -78,7 +78,7 @@ jobs:
           retention-days: 1
 
   macOS:
-    runs-on: macos-10.15
+    runs-on: macos-11
     steps:
       - uses: actions/checkout@v3
         with:
@@ -91,27 +91,36 @@ jobs:
         run: printf 'NVIM_BUILD_TYPE=Release\n' >> $GITHUB_ENV
       - if: github.event_name == 'schedule' || (github.event_name == 'workflow_dispatch' && github.event.inputs.tag_name == 'nightly')
         run: printf 'NVIM_BUILD_TYPE=RelWithDebInfo\n' >> $GITHUB_ENV
+      - name: Provision universal `libintl`
+        run: |
+          GETTEXT_PREFIX="$(brew --prefix gettext)"
+          printf 'GETTEXT_PREFIX=%s\n' "$GETTEXT_PREFIX" >> $GITHUB_ENV
+          bottle_tag="arm64_big_sur"
+          brew fetch --bottle-tag="$bottle_tag" gettext
+          cd "$(mktemp -d)"
+          tar xf "$(brew --cache)"/**/*gettext*${bottle_tag}*.tar.gz
+          lipo gettext/*/lib/libintl.a "${GETTEXT_PREFIX}/lib/libintl.a" -create -output libintl.a
+          mv -f libintl.a /usr/local/lib/
+      - name: Ensure static linkage to `libintl`
+        run: |
+          # We're about to mangle `gettext`, so let's remove any potentially broken
+          # installs (e.g. curl, git) as those could interfere with our build.
+          brew uninstall $(brew uses --installed --recursive gettext)
+          brew unlink gettext
+          ln -sf "$(brew --prefix)/opt/$(readlink "${GETTEXT_PREFIX}")/bin"/* /usr/local/bin/
+          rm -f "$GETTEXT_PREFIX"
       - name: Build release
         run: |
-          make CMAKE_BUILD_TYPE=${NVIM_BUILD_TYPE} CMAKE_EXTRA_FLAGS="-DCMAKE_INSTALL_PREFIX:PATH= -DCMAKE_OSX_DEPLOYMENT_TARGET=10.11"
-          make DESTDIR="$GITHUB_WORKSPACE/build/release/nvim-osx64" install
+          export MACOSX_DEPLOYMENT_TARGET="$(sw_vers -productVersion | cut -f1 -d.)"
+          OSX_FLAGS="-DCMAKE_OSX_DEPLOYMENT_TARGET=${MACOSX_DEPLOYMENT_TARGET} -DCMAKE_OSX_ARCHITECTURES=arm64\;x86_64"
+          make CMAKE_BUILD_TYPE=${NVIM_BUILD_TYPE} \
+               CMAKE_EXTRA_FLAGS="-DCMAKE_INSTALL_PREFIX:PATH= $OSX_FLAGS" \
+               DEPS_CMAKE_FLAGS="$OSX_FLAGS"
+          make DESTDIR="$GITHUB_WORKSPACE/build/release/nvim-macos" install
       - name: Create package
         run: |
           cd "$GITHUB_WORKSPACE/build/release"
-          mkdir -p nvim-osx64/libs
-          libs=($(otool -L nvim-osx64/bin/nvim | sed 1d | sed -E -e 's|^[[:space:]]*||' -e 's| .*||'))
-          echo "libs:"
-          for lib in "${libs[@]}"; do
-            if echo "$lib" | grep -q -E 'libSystem|CoreServices' 2>/dev/null; then
-              echo "  [skipped] $lib"
-            else
-              echo "  $lib"
-              relname="libs/${lib##*/}"
-              cp -L "$lib" "nvim-osx64/$relname"
-              install_name_tool -change "$lib" "@executable_path/../$relname" nvim-osx64/bin/nvim
-            fi
-          done
-          tar cfz nvim-macos.tar.gz nvim-osx64
+          tar cfz nvim-macos.tar.gz nvim-macos
       - uses: actions/upload-artifact@v3
         with:
           name: nvim-macos