Make the FBMacDevice use a unique auxiliar dir

Summary: This prevents data races when running macOS tests simultaneously on the same host with multiple companions.

Reviewed By: lawrencelomax

Differential Revision: D30045850

fbshipit-source-id: 79e1a92d36d3f3f1245b9bd5e862c3d42037f21d

XCTestBootstrap/MacStrategies/FBMacDevice.m

@@ -64,7 +64,7 @@ - (instancetype)init
   if (self) {
     _architecture = FBArchitectureX86_64;
     _asyncQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);
-    _auxillaryDirectory = NSTemporaryDirectory();
+    _auxillaryDirectory = [NSTemporaryDirectory() stringByAppendingPathComponent:NSProcessInfo.processInfo.globallyUniqueString];
     _bundleIDToProductMap = [FBMacDevice fetchInstalledApplications];
     _bundleIDToRunningTask = @{}.mutableCopy;
     _launchdProcess = [[FBProcessInfo alloc] initWithProcessIdentifier:1 launchPath:@"/sbin/launchd" arguments:@[] environment:@{}];