macOS V2 Sandbox: Allow lsd.mapdb service in the GPU.

This attempts to address crashes where the GPU process is hanging trying
to contact launchservicesd. It attempts to address these crashes by
allowing access to the lsdb.mapdb launchservices endpoint, which exposes
less attack surface than the full launchservicesd.

Bug: 812228
Change-Id: I1f44bad960d1d07fda622a4d5ad957b281c96792
Reviewed-on: https://chromium-review.googlesource.com/923126Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Greg Kerr <kerrnel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537356}

services/service_manager/sandbox/mac/gpu_v2.sb

@@ -8,6 +8,7 @@
 (allow mach-lookup
   (global-name "com.apple.CoreServices.coreservicesd")
   (global-name "com.apple.cvmsServ")
+  (global-name "com.apple.lsd.mapdb")
   (global-name "com.apple.system.notification_center")
   (global-name "com.apple.tsm.uiserver")
   (global-name "com.apple.windowserver.active"))