Add matrix testing to GitHub Actions CI

GitHub Actions runners choices are relatively limited, so do matrix
testing on the two OS versions they support, and Xcode 11 to test
compatibility with Catalina (10.15) SDKs.

Remove the standard Vim's CI file, to make it less confusing and to
prevent GitHub Actions from running it accidentally (the UI has the
ability to disable certain workflows but it seems a little buggy at
times).

Also fixed up how terminal Vim was linking against Carbon and Cocoa
which are unnecessary. It only needs AppKit for communicating between
MMBackend and the GUI.

Also switch to using clang to match what we had in Travis CI.

Author: ychin

.github/workflows/ci-macvim.yaml

@@ -7,6 +7,9 @@ on:
 env:
   MACOSX_DEPLOYMENT_TARGET: 10.9
 
+  CC: clang
+  CONFOPT: "--with-features=huge --enable-netbeans --with-tlib=ncurses --enable-cscope --enable-gui=macvim --with-macarchs=x86_64"
+
   VERSIONER_PERL_VERSION: 5.18
   VERSIONER_PYTHON_VERSION: 2.7
   vi_cv_path_python: /usr/bin/python
@@ -17,23 +20,38 @@ env:
   vi_cv_dll_name_python: /System/Library/Frameworks/Python.framework/Versions/2.7/Python
   vi_cv_dll_name_python3: /usr/local/Frameworks/Python.framework/Versions/3.9/Python
   vi_cv_dll_name_ruby: /usr/local/opt/ruby/lib/libruby.dylib
+  LANGOPT: "--enable-perlinterp=dynamic --enable-pythoninterp=dynamic --enable-python3interp=dynamic --enable-rubyinterp=dynamic --enable-luainterp=dynamic --with-lua-prefix=/usr/local"
 
   VIMCMD: src/MacVim/build/Release/MacVim.app/Contents/MacOS/Vim
   MACVIM_BIN: src/MacVim/build/Release/MacVim.app/Contents/MacOS/MacVim
 
-  CONFOPT: "--with-features=huge --enable-netbeans --with-tlib=ncurses --enable-cscope --enable-gui=macvim --with-macarchs=x86_64"
-  LANGOPT: "--enable-perlinterp=dynamic --enable-pythoninterp=dynamic --enable-python3interp=dynamic --enable-rubyinterp=dynamic --enable-luainterp=dynamic --with-lua-prefix=/usr/local"
-
   HAS_GETTEXT: 1
 
-  BASH_SILENCE_DEPRECATION_WARNING: 1
   TERM: xterm
+  BASH_SILENCE_DEPRECATION_WARNING: 1
 
 jobs:
 
   # Builds and test MacVim
   build:
-    runs-on: macos-latest
+
+    # Test on macOS 10.15 / 11.0, and also older version of Xcode for compatibility testing.
+    strategy:
+      fail-fast: false
+      matrix:
+        xcode: ['']
+        os: [macos-10.15, macos-11.0]
+        include:
+        - os: macos-10.15
+          xcode: 11.7
+        - os: macos-10.15
+          xcode: ''
+          publish: true
+
+    runs-on: ${{ matrix.os }}
+
+    env:
+      XCODE_VER: ${{ matrix.xcode }}
 
     steps:
     - uses: actions/checkout@v2
@@ -89,6 +107,11 @@ jobs:
         set -o errexit
         set -o verbose
 
+        if [[ -n "${XCODE_VER}" ]]; then
+          sudo xcode-select -s /Applications/Xcode_${XCODE_VER}.app/Contents/Developer
+        fi
+        xcode-select -p
+
         ./configure ${CONFOPT} ${LANGOPT} --enable-fail-if-missing
         sed -i.bak -f ci/config.mk.sed -f ci/config.mk.clang.sed src/auto/config.mk
         # Ruby is keg-only in Homebrew, so need to manually link in the path so Vim will know where to look for the binaries.
@@ -155,14 +178,14 @@ jobs:
     # do it manually, for two reasons: 1) signing / notarization are currently done out of CI, 2) we want to manually
     # format our release notes and add pictures to make them look nice.
     - name: Build MacVim dmg image
-      if: startsWith(github.ref, 'refs/tags/')
+      if: startsWith(github.ref, 'refs/tags/') && matrix.publish
       run: |
         # Use the --skip-jenkins flag to skip the prettify osascript calls which could fail due to permission issues in
         # CI environment.
         make -C src macvim-dmg CREATEDMG_FLAGS=--skip-jenkins
 
     - name: Upload MacVim image
-      if: startsWith(github.ref, 'refs/tags/')
+      if: startsWith(github.ref, 'refs/tags/') && matrix.publish
       uses: actions/upload-artifact@v2
       with:
         name: MacVim.dmg