In native coverage builds, allow all domains to access /data/misc/trace

Bug: http://b/135139675

Coverage files are written to /data/misc/trace (governed by the
method_trace_data_file selinux type).  Allow all domains to access
(create directories, access files) this directory when native coverage
is enabled (by setting NATIVE_COVERAGE to true) in an userdebug or eng
build.

Also relax neverallow constraints to allow access to
method_trace_data_file for native coverage builds.

Test: Build 32-bit cuttlefish with coverage:
          m NATIVE_COVERAGE=true COVERAGE_PATHS="*"
      and verify that there are no selinux denials in kernel log and
      logcat.

Change-Id: I3fe7c77612854b9de7de7a0ddd5cbf44a2f5c21e
diff --git a/private/traced_probes.te b/private/traced_probes.te
index d8d573a..8746c34 100644
--- a/private/traced_probes.te
+++ b/private/traced_probes.te
@@ -111,11 +111,17 @@
   # subsequent neverallow. Currently only getattr and search are allowed.
   -vendor_data_file
   -zoneinfo_data_file
+  with_native_coverage(`-method_trace_data_file')
 }:dir *;
 neverallow traced_probes system_data_file:dir ~{ getattr userdebug_or_eng(`open read') search };
 neverallow traced_probes zoneinfo_data_file:dir ~r_dir_perms;
 neverallow traced_probes { data_file_type -zoneinfo_data_file }:lnk_file *;
-neverallow traced_probes { data_file_type -zoneinfo_data_file -packages_list_file }:file *;
+neverallow traced_probes {
+  data_file_type
+  -zoneinfo_data_file
+  -packages_list_file
+  with_native_coverage(`-method_trace_data_file')
+}:file *;
 
 # Only init is allowed to enter the traced_probes domain via exec()
 neverallow { domain -init } traced_probes:process transition;