Add some checks for the tools we need

May not be exhastive, but useful on Windows where you need to
remember to install stuff.

hak/matrix-seshat/check.js

@@ -0,0 +1,57 @@
+/*
+Copyright 2020 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.
+*/
+
+const childProcess = require('child_process');
+
+module.exports = async function(hakEnv, moduleInfo) {
+    // of course tcl doesn't have a --version
+    await new Promise((resolve, reject) => {
+        const proc = childProcess.spawn('tclsh', [], {
+            stdio: ['pipe', 'ignore', 'ignore'],
+        });
+        proc.on('exit', (code) => {
+            if (code !== 0) {
+                reject("Can't find tclsh - have you installed TCL?");
+            } else {
+                resolve();
+            }
+        });
+        proc.stdin.end();
+    });
+
+    const tools = [];
+    if (hakEnv.isWin()) {
+        tools.push('perl'); // for openssl configure
+        tools.push('nmake');
+    } else {
+        tools.push('make');
+    }
+
+    for (const tool of tools) {
+        await new Promise((resolve, reject) => {
+            const proc = childProcess.spawn(tool, ['--version'], {
+                stdio: ['ignore'],
+            });
+            proc.on('exit', (code) => {
+                if (code !== 0) {
+                    reject("Can't find " + tool);
+                } else {
+                    resolve();
+                }
+            });
+        });
+    }
+};

scripts/hak/index.js

@@ -26,6 +26,7 @@ const GENERALCOMMANDS = [
 
 // These can only be run on specific modules
 const MODULECOMMANDS = [
+    'check',
     'fetch',
     'link',
     'fetchDeps',
@@ -34,7 +35,9 @@ const MODULECOMMANDS = [
     'clean',
 ];
 
+// Scripts valid in a hak.json 'scripts' section
 const HAKSCRIPTS = [
+    'check',
     'fetch',
     'fetchDeps',
     'build',