profman/debuggerd: allow libart_file:file r_file_perms

Addresses the following auditallow spam:

avc: granted { read open } for comm="profman"
path="/system/lib/libart.so" dev="dm-0" ino=1368 scontext=u:r:profman:s0
tcontext=u:object_r:libart_file:s0 tclass=file

avc: granted { read open } for comm="debuggerd64"
path="/system/lib64/libart.so" dev="dm-0" ino=1897
scontext=u:r:debuggerd:s0 tcontext=u:object_r:libart_file:s0 tclass=file

avc: granted { getattr } for comm="debuggerd64"
path="/system/lib64/libart.so" dev="dm-0" ino=1837
scontext=u:r:debuggerd:s0 tcontext=u:object_r:libart_file:s0 tclass=file

Test: Policy compiles. Not a tightening of rules.
Change-Id: I501b0a6a343c61b3ca6283647a18a9a15deddf2a
diff --git a/public/debuggerd.te b/public/debuggerd.te
index da1314a..33f8878 100644
--- a/public/debuggerd.te
+++ b/public/debuggerd.te
@@ -23,7 +23,7 @@
 allow debuggerd shared_relro_file:dir r_dir_perms;
 allow debuggerd shared_relro_file:file r_file_perms;
 allow debuggerd domain:process { sigstop sigkill signal };
-allow debuggerd exec_type:file r_file_perms;
+allow debuggerd { exec_type libart_file }:file r_file_perms;
 # Access app library
 allow debuggerd system_data_file:file open;
 # Allow debuggerd to redirect a dump_backtrace request to itself.