label app_process64 as zygote_exec

... otherwise zygote 64 won't run in the correct SELinux domain.

Bug: 13647418
Change-Id: Iada2bf26623784535b70647c472f69b735b8f4fc

file_contexts

@@ -122,6 +122,7 @@
 /system/bin/run-as	--	u:object_r:runas_exec:s0
 /system/bin/bootanimation u:object_r:bootanim_exec:s0
 /system/bin/app_process	u:object_r:zygote_exec:s0
+/system/bin/app_process64	u:object_r:zygote_exec:s0
 /system/bin/servicemanager	u:object_r:servicemanager_exec:s0
 /system/bin/surfaceflinger	u:object_r:surfaceflinger_exec:s0
 /system/bin/drmserver	u:object_r:drmserver_exec:s0