Resubmit: Clean up .bazelrc for MacOS.

This time, don't move `--enable_platform_specific_config` because it affects the expanded flag order.

PiperOrigin-RevId: 363584510
Change-Id: I2290305f280f71e469fea9c64307d59b5cc336a5

.bazelrc

@@ -120,7 +120,13 @@ build:android_x86_64 --cpu=x86_64
 build:android_x86_64 --fat_apk_cpu=x86_64
 
 # Sets the default Apple platform to macOS.
-build --apple_platform_type=macos
+build:macos --apple_platform_type=macos
+
+# gRPC on MacOS requires this #define
+build:macos --copt=-DGRPC_BAZEL_BUILD
+
+# Settings for MacOS on ARM CPUs.
+build:macos_arm64 --cpu=darwin_arm64
 
 # iOS configs for each architecture and the fat binary builds.
 build:ios --apple_platform_type=ios
@@ -137,11 +143,6 @@ build:ios_x86_64 --cpu=ios_x86_64
 build:ios_fat --config=ios
 build:ios_fat --ios_multi_cpus=armv7,arm64,i386,x86_64
 
-# Enables all the macos config options for macos_arm64
-build:macos_arm64 --config=macos
-build:macos_arm64 --apple_platform_type=macos
-build:macos_arm64 --cpu=darwin_arm64
-
 # For projects which use TensorFlow as part of a Bazel build process, putting
 # nothing in a bazelrc will default to a monolithic build. The following line
 # opts in to modular op registration support by default.
@@ -262,12 +263,10 @@ build:c++1z --config=c++17
 build:c++17_gcc --cxxopt=-std=c++1z
 build:c++1z_gcc --config=c++17_gcc
 
-# Enable using platform specific build settings, except when cross-compiling for
-# mobile platforms.
+# Trigger --config=<host platform>, except when cross-compiling.
 build --enable_platform_specific_config
 build:android --noenable_platform_specific_config
 build:ios --noenable_platform_specific_config
-build:macos_arm64 --noenable_platform_specific_config
 
 # Suppress C++ compiler warnings, otherwise build logs become 10s of MBs.
 build:android --copt=-w