fix: resolve compiled output from dist in bin and postinstall

Both resolve into lib/ relative to their own location, which stopped working
when the build moved output to dist/: lib/ now holds only TypeScript, so
running ./bin/tns or postinstall.js from a checkout fails with
MODULE_NOT_FOUND. The published package is unaffected, since dist/ is its
root and lib/ already sits next to bin/ there.

Both now prefer dist/lib when it exists and fall back otherwise, which covers
the checkout and the package without either needing to know which it is. The
other bin entries delegate to ./tns, so they are fixed with it.

npm install in a checkout runs postinstall and would hit the same failure -
masked only because npm run setup passes --ignore-scripts.

Author: edusperoni

bin/tns

@@ -2,7 +2,14 @@
 
 "use strict";
 var path = require("path"),
-	pathToLib = path.join(__dirname, "..", "lib"),
+	fs = require("fs"),
+	// In the published package dist/ is the root, so lib/ already sits next to
+	// bin/. In a source checkout lib/ holds only TypeScript and the compiled
+	// output lives under dist/.
+	distLib = path.join(__dirname, "..", "dist", "lib"),
+	pathToLib = fs.existsSync(distLib)
+		? distLib
+		: path.join(__dirname, "..", "lib"),
 	pathToCommon = path.join(pathToLib, "common");
 
 require(path.join(pathToCommon, "verify-node-version")).verifyNodeVersion();

postinstall.js

@@ -2,9 +2,14 @@
 
 var child_process = require("child_process");
 var path = require("path");
-var constants = require(path.join(__dirname, "lib", "constants"));
+var fs = require("fs");
+// In the published package dist/ is the root; in a source checkout the compiled
+// output lives under dist/ while lib/ holds only TypeScript.
+var distLib = path.join(__dirname, "dist", "lib");
+var pathToLib = fs.existsSync(distLib) ? distLib : path.join(__dirname, "lib");
+var constants = require(path.join(pathToLib, "constants"));
 var commandArgs = [path.join(__dirname, "bin", "tns"), constants.POST_INSTALL_COMMAND_NAME];
-var helpers = require(path.join(__dirname, "lib", "common", "helpers"));
+var helpers = require(path.join(pathToLib, "common", "helpers"));
 if (helpers.isInstallingNativeScriptGlobally()) {
 	child_process.spawn(process.argv[0], commandArgs, { stdio: "inherit" });
 }