Explicitly distinguish windows and osx x86 vs arm64 (#30)

The windows platform didn't distinguish x86 vs arm64, which was causing
x86 binaries to be used when building for arm64.  Do better.

OSX had similar problems, add definitions to support distinguishing
those.

Signed-off-by: Austin Schuh <austin.linux@gmail.com>

Author: AustinSchuh

conditions/BUILD.bazel

@@ -1,13 +1,19 @@
 # Mimics @bazel_tools/src/conditions:windows
 config_setting(
-    name = "windows",
-    constraint_values = ["@platforms//os:windows"],
+    name = "windows_x86_64",
+    constraint_values = [
+        "@platforms//os:windows",
+        "@platforms//cpu:x86_64",
+    ],
     visibility = ["//visibility:public"],
 )
 
 config_setting(
-    name = "windows_debug",
-    constraint_values = ["@platforms//os:windows"],
+    name = "windows_x86_64_debug",
+    constraint_values = [
+        "@platforms//os:windows",
+        "@platforms//cpu:x86_64",
+    ],
     values = {
         "compilation_mode": "dbg",
     },
@@ -19,20 +25,18 @@ config_setting(
     name = "windows_arm64",
     constraint_values = [
         "@platforms//os:windows",
-        "@platforms//cpu:x86_64",
+        "@platforms//cpu:aarch64",
     ],
-    values = {"cpu": "x64_arm64_windows"},
 )
 
 config_setting(
     name = "windows_arm64_debug",
     constraint_values = [
         "@platforms//os:windows",
-        "@platforms//cpu:x86_64",
+        "@platforms//cpu:aarch64",
     ],
     values = {
         "compilation_mode": "dbg",
-        "cpu": "x64_arm64_windows",
     },
     visibility = ["//visibility:public"],
 )
@@ -75,6 +79,24 @@ config_setting(
     visibility = ["//visibility:public"],
 )
 
+config_setting(
+    name = "osx_x86_64",
+    constraint_values = [
+        "@platforms//os:osx",
+        "@platforms//cpu:x86_64",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+config_setting(
+    name = "osx_aarch64",
+    constraint_values = [
+        "@platforms//os:osx",
+        "@platforms//cpu:aarch64",
+    ],
+    visibility = ["//visibility:public"],
+)
+
 # Custom definitions
 
 # Linux - 64-bit arm