Borrow target definition from electron-builder

A bit hacky, but for now we paste in the JS generated version of the builder's
`target.ts` module. It's quite unlikely to change often, so this is perhaps
enough for now.

scripts/hak/target.js

@@ -0,0 +1,60 @@
+"use strict";
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.ENABLED_TARGETS = exports.TARGETS = void 0;
+const aarch64AppleDarwin = {
+    id: 'aarch64-apple-darwin',
+    platform: 'darwin',
+    arch: 'arm64',
+};
+const i686PcWindowsMsvc = {
+    id: 'i686-pc-windows-msvc',
+    platform: 'win32',
+    arch: 'ia32',
+    vcVarsArch: 'x86',
+};
+const x8664PcWindowsMsvc = {
+    id: 'x86_64-pc-windows-msvc',
+    platform: 'win32',
+    arch: 'x64',
+    vcVarsArch: 'amd64',
+};
+const x8664AppleDarwin = {
+    id: 'x86_64-apple-darwin',
+    platform: 'darwin',
+    arch: 'x64',
+};
+const x8664UnknownLinuxGnu = {
+    id: 'x86_64-unknown-linux-gnu',
+    platform: 'linux',
+    arch: 'x64',
+};
+exports.TARGETS = {
+    'aarch64-apple-darwin': aarch64AppleDarwin,
+    'i686-pc-windows-msvc': i686PcWindowsMsvc,
+    'x86_64-pc-windows-msvc': x8664PcWindowsMsvc,
+    'x86_64-apple-darwin': x8664AppleDarwin,
+    'x86_64-unknown-linux-gnu': x8664UnknownLinuxGnu,
+};
+// The set of targets we build by default, sorted by increasing complexity so
+// that we fail fast when the native host target fails.
+exports.ENABLED_TARGETS = [
+    exports.TARGETS['x86_64-apple-darwin'],
+    exports.TARGETS['aarch64-apple-darwin'],
+    exports.TARGETS['x86_64-unknown-linux-gnu'],
+    exports.TARGETS['i686-pc-windows-msvc'],
+];