fix(mac): ENOENT for symlinks because directory was not created

[heinzbeinz]

We got a problem while building with the latest version of electron builder. Our extraResources contains symbolic links and electron builder failed to create those links with:

Error: ENOENT: no such file or directory, symlink 'Resources/x2go-X11/lib/' -> '/Users/fastlane/devel/rl3client/client/dist/mac/RemoteLabs3Client.app/Contents/Resources/electron-app/x2goclient.app/Contents/lib'
    at Error (native)
From previous event:
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/util/fs.ts:178:13
    at next (native)
From previous event:
    at walk (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/util/fs.js:236:26)
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/util/fs.ts:74:44
From previous event:
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/util/fs.ts:62:10
    at /Users/fastlane/devel/rl3client/client/node_modules/graceful-fs/polyfills.js:287:18
From previous event:
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/util/fs.ts:59:27
    at next (native)
    at go$readdir$cb (/Users/fastlane/devel/rl3client/client/node_modules/graceful-fs/graceful-fs.js:149:14)
    at FSReqWrap.oncomplete (fs.js:123:15)
From previous event:
    at walk (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/util/fs.js:90:22)
    at copyDir (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/util/fs.ts:176:3)
    at default.map.pattern (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/platformPackager.ts:349:14)
From previous event:
    at MacPackager.doCopyExtraFiles (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/platformPackager.ts:345:28)
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/platformPackager.ts:281:16
    at next (native)
    at runCallback (timers.js:637:20)
    at tryOnImmediate (timers.js:610:5)
    at processImmediate [as _immediateCallback] (timers.js:582:5)
From previous event:
    at MacPackager.doPack (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/platformPackager.js:321:11)
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/macPackager.ts:78:28
    at next (native)
From previous event:
    at MacPackager.pack (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/macPackager.js:162:11)
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/packager.ts:146:22
From previous event:
    at Packager.doBuild (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/packager.js:271:11)
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/packager.ts:114:38
    at next (native)
    at runCallback (timers.js:637:20)
    at tryOnImmediate (timers.js:610:5)
    at processImmediate [as _immediateCallback] (timers.js:582:5)
From previous event:
    at Packager.build (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/packager.js:223:11)
    at /Users/fastlane/devel/rl3client/client/node_modules/electron-builder/src/builder.ts:241:40
    at next (native)
From previous event:
    at build (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/builder.js:89:21)
    at Object.<anonymous> (/Users/fastlane/devel/rl3client/client/node_modules/electron-builder/out/cli/build-cli.js:68:41)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:509:3
child process exited with code 255

The fix creates the directory before attempting to create the symlinks.

[develar]

Duplicates #998 :) I am working on test and it will be merged soon.