Exclude isolated_app from ptrace self.

Change-Id: I29136a805d2329806afc9d5d81af934a1803d8e0
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

app.te

@@ -19,7 +19,7 @@ allow appdomain zygote:fd use;
 allow appdomain zygote_exec:file rx_file_perms;
 
 # gdbserver for ndk-gdb ptrace attaches to app process.
-allow appdomain self:process ptrace;
+allow { appdomain -isolated_app } self:process ptrace;
 
 # Read system properties managed by zygote.
 allow appdomain zygote_tmpfs:file read;