Make chooseAsset more precise: search for clangd-<platform>. (#7)

Previously we just searched for <platform> which matched our indexer
releases, oops!

Author: sam-mccall

src/index.ts

@@ -194,7 +194,8 @@ export async function chooseAsset(release: Github.Release):
                   // Mac distribution contains a fat binary working on both x64
                   // and arm64s.
                   (os.arch() == 'arm64' && variant == 'mac'))) {
-    const asset = release.assets.find(a => a.name.indexOf(variant) >= 0);
+    const substr = 'clangd-' + variant;
+    const asset = release.assets.find(a => a.name.indexOf(substr) >= 0);
     if (asset)
       return asset;
   }

test/assets/release.json

@@ -33,6 +33,40 @@
   "created_at": "2020-02-20T12:44:25Z",
   "published_at": "2020-03-10T09:42:12Z",
   "assets": [
+    {
+      "url": "http://api.github.com/repos/clangd/clangd/releases/assets/18600444",
+      "id": 18600444,
+      "node_id": "MDEyOlJlbGVhc2VBc3NldDE4NjAwNDQ0",
+      "name": "clangd-indexing-tools-linux-10.zip",
+      "label": "",
+      "uploader": {
+        "login": "clangd-build",
+        "id": 60678011,
+        "node_id": "MDQ6VXNlcjYwNjc4MDEx",
+        "avatar_url": "https://avatars2.githubusercontent.com/u/60678011?v=4",
+        "gravatar_id": "",
+        "url": "https://api.github.com/users/clangd-build",
+        "html_url": "https://github.com/clangd-build",
+        "followers_url": "https://api.github.com/users/clangd-build/followers",
+        "following_url": "https://api.github.com/users/clangd-build/following{/other_user}",
+        "gists_url": "https://api.github.com/users/clangd-build/gists{/gist_id}",
+        "starred_url": "https://api.github.com/users/clangd-build/starred{/owner}{/repo}",
+        "subscriptions_url": "https://api.github.com/users/clangd-build/subscriptions",
+        "organizations_url": "https://api.github.com/users/clangd-build/orgs",
+        "repos_url": "https://api.github.com/users/clangd-build/repos",
+        "events_url": "https://api.github.com/users/clangd-build/events{/privacy}",
+        "received_events_url": "https://api.github.com/users/clangd-build/received_events",
+        "type": "User",
+        "site_admin": false
+      },
+      "content_type": "application/zip",
+      "state": "uploaded",
+      "size": 46545010,
+      "download_count": 615,
+      "created_at": "2020-03-10T09:22:40Z",
+      "updated_at": "2020-03-10T09:22:41Z",
+      "browser_download_url": "http://localhost:9999/does-not-exist.zip"
+    },
     {
       "url": "http://api.github.com/repos/clangd/clangd/releases/assets/18600444",
       "id": 18600444,