Let fallback crash dumping write to dumpstate pipes.

Fix the following denial:
    avc: denied { append } for pid=1093 comm="mediaextractor" path="pipe:[68438]" dev="pipefs" ino=68438 scontext=u:r:mediaextractor:s0 tcontext=u:r:dumpstate:s0 tclass=fifo_file permissive=1 ppid=1 pcomm="init" pgid=1 pgcomm="init"

Bug: http://b/38444258
Test: none
Change-Id: I58162e3a28b744a58396e77d6b0e2becb5633d6a

public/te_macros

@@ -458,6 +458,7 @@ userdebug_or_eng(`
   allow $1 su:fifo_file append;
 ')
 allow $1 anr_data_file:file append;
+allow $1 dumpstate:fifo_file append;
 allow $1 tombstoned:unix_stream_socket connectto;
 allow $1 tombstoned:fd use;
 allow $1 tombstoned_crash_socket:sock_file write;