Allow mediaextractor/mediacodec to connect to tombstoned.

Whitelist recvmsg so that mediaextractor and mediacodec can get an
output fd from tombstoned.

Bug: http://b/35858739
Test: debuggerd -b `pidof media.codec`
Change-Id: I2126da6c77bde739ae37c48b1a13dcefc6482a64
diff --git a/services/mediacodec/seccomp_policy/mediacodec-arm.policy b/services/mediacodec/seccomp_policy/mediacodec-arm.policy
index 081caf0..890d777 100644
--- a/services/mediacodec/seccomp_policy/mediacodec-arm.policy
+++ b/services/mediacodec/seccomp_policy/mediacodec-arm.policy
@@ -63,3 +63,4 @@
 getgid32: 1
 getegid32: 1
 getgroups32: 1
+recvmsg: 1