[CI] Cross-compile Intel Mac release binary

Follow-up to #2958, where we added and tested cross-compilation support. This
allows us to use Xcode 16 to compile the Intel Mac binary (macos-15 is Apple
Silicon-based, macos-13 only has Xcode 15 available) and take advantage of the
faster M1-based runners.

- Don't set minimum macOS version for host configuration, host tools are only
  needed during the build and do not need to be distributed beyond that. This
  fixes a misleading warning.

.bazelrc

@@ -211,8 +211,9 @@ build:linux --config=unix
 build:macos --config=unix
 
 # Support macOS 13 as the minimum version. There should be at least a warning when backward
-# compatibility is broken as -Wunguarded-availability-new is enabled by default.
-build:macos --macos_minimum_os=13.5 --host_macos_minimum_os=13.5
+# compatibility is broken as -Wunguarded-availability-new is enabled by default. Only enable for
+# target configuration as host configuration tools are only used during the build process.
+build:macos --macos_minimum_os=13.5
 
 # Avoid emitting duplicate unwind info where compact unwind info can be used. This reduces the
 # object size by ~5% on average, improving disk space usage and link times. The final binary size

.github/workflows/release.yml

@@ -56,13 +56,13 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ubuntu-20.04, macos-13, windows-2022]
+        os: [ubuntu-20.04, macos-15, windows-2022]
         include:
           - os-name: linux
             os: ubuntu-20.04
             bazel-config: release_linux
           - os-name: macOS
-            os: macos-13
+            os: macos-15
             bazel-config: release_macos
           - os-name: windows
             os: windows-2022
@@ -95,11 +95,12 @@ jobs:
       - name: Setup macOS
         if: runner.os == 'macOS'
         run: |
-          sudo xcode-select -s "/Applications/Xcode_15.1.app"
           # Install lld and link it to /usr/local/bin. We overwrite any existing link, which may
           # exist from an older pre-installed LLVM version on the runner image.
           brew install lld
           sudo ln -s -f $(brew --prefix lld)/bin/ld64.lld /usr/local/bin/ld64.lld
+          # Cross-compile so that we can use the latest Xcode version for the Intel Mac binary
+          echo "build:macos --config=macos-cross-x86_64" >> .bazelrc
           # Enable lld identical code folding to significantly reduce binary size.
           echo "build:macos --config=macos_lld_icf" >> .bazelrc
       - name: Setup Windows