(bazel) Set @platforms//os:emscripten for platform_wasm (#1363)

* (bazel) Set @platforms//os:emscripten for platform_wasm

* (bazel) Set @platforms//os:emscripten for platform_wasm

* (bazel) Set @platforms//os:emscripten for platform_wasm

bazel/BUILD

@@ -82,6 +82,7 @@ platform(
     name = "platform_wasm",
     constraint_values = [
         "@platforms//cpu:wasm32",
+        "@platforms//os:emscripten",
     ],
 )
 

bazel/MODULE.bazel

@@ -0,0 +1 @@
+bazel_dep(name = "platforms", version = "0.0.9")

bazel/README.md

@@ -26,6 +26,11 @@ The SHA1 hash in the above `strip_prefix` and `url` parameters correspond to the
 newer versions, you'll need to update those. To make use of older versions, change the
 parameter of `emsdk_emscripten_deps()`. Supported versions are listed in `revisions.bzl`
 
+Bazel 7+ additionally requires `platforms` dependencies in the `MODULE.bazel` file.
+```starlark
+bazel_dep(name = "platforms", version = "0.0.9")
+```
+
 
 ## Building
 

bazel/deps.bzl

@@ -2,6 +2,15 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 
 def deps():
+    maybe(
+        http_archive,
+        name = "platforms",
+        urls = [
+            "https://mirror.bazel.build/github.com/bazelbuild/platforms/releases/download/0.0.9/platforms-0.0.9.tar.gz",
+            "https://github.com/bazelbuild/platforms/releases/download/0.0.9/platforms-0.0.9.tar.gz",
+        ],
+        sha256 = "5eda539c841265031c2f82d8ae7a3a6490bd62176e0c038fc469eabf91f6149b",
+    )
     maybe(
         http_archive,
         name = "bazel_skylib",

bazel/test_external/MODULE.bazel

@@ -0,0 +1 @@
+bazel_dep(name = "platforms", version = "0.0.9")