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.te b/private/traced.te
index 1e2d7d6..2d7d07f 100644
--- a/private/traced.te
+++ b/private/traced.te
@@ -66,6 +66,7 @@
   # 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 { system_data_file }:dir ~{ getattr search };
 neverallow traced zoneinfo_data_file:dir ~r_dir_perms;
@@ -75,6 +76,7 @@
   -zoneinfo_data_file
   -perfetto_traces_data_file
   -trace_data_file
+  with_native_coverage(`-method_trace_data_file')
 }:file ~write;
 
 # Only init is allowed to enter the traced domain via exec()