Move __system_property* to LIBC_PRIVATE for lp64 libc

Bug: http://b/26367254
Change-Id: I4fc241e69444a4b5641dfdf09576fe3ce5c1169e
diff --git a/libc/libc.arm.brillo.map b/libc/libc.arm.brillo.map
index 8cbff2b..85ded30 100644
--- a/libc/libc.arm.brillo.map
+++ b/libc/libc.arm.brillo.map
@@ -187,21 +187,21 @@
     __sym_ntop;
     __sym_ntos;
     __sym_ston;
-    __system_properties_init;
-    __system_property_add;
-    __system_property_area__;
-    __system_property_area_init;
-    __system_property_area_serial;
-    __system_property_find;
-    __system_property_find_nth;
-    __system_property_foreach;
-    __system_property_get;
-    __system_property_read;
-    __system_property_serial;
-    __system_property_set;
-    __system_property_set_filename;
-    __system_property_update;
-    __system_property_wait_any;
+    __system_properties_init; # arm x86 mips
+    __system_property_add; # arm x86 mips
+    __system_property_area__; # arm x86 mips
+    __system_property_area_init; # arm x86 mips
+    __system_property_area_serial; # arm x86 mips
+    __system_property_find; # arm x86 mips
+    __system_property_find_nth; # arm x86 mips
+    __system_property_foreach; # arm x86 mips
+    __system_property_get; # arm x86 mips
+    __system_property_read; # arm x86 mips
+    __system_property_serial; # arm x86 mips
+    __system_property_set; # arm x86 mips
+    __system_property_set_filename; # arm x86 mips
+    __system_property_update; # arm x86 mips
+    __system_property_wait_any; # arm x86 mips
     __timer_create; # arm x86 mips
     __timer_delete; # arm x86 mips
     __timer_getoverrun; # arm x86 mips