Introduce crash_dump debugging helper.

Replace the global debuggerd with a per-process debugging helper that
gets exec'ed by the process that crashed.

Bug: http://b/30705528
Test: crasher/crasher64, `debuggerd <pid>`, `kill -ABRT <pid>`
Change-Id: Iad1b7478f7a4e2690720db4b066417d8b66834ed
diff --git a/public/domain_deprecated.te b/public/domain_deprecated.te
index d092d09..1f535c3 100644
--- a/public/domain_deprecated.te
+++ b/public/domain_deprecated.te
@@ -123,5 +123,5 @@
 # Get SELinux enforcing status.
 allow domain_deprecated selinuxfs:dir r_dir_perms;
 allow domain_deprecated selinuxfs:file r_file_perms;
-auditallow { domain_deprecated -appdomain -debuggerd -init -installd -keystore -postinstall_dexopt -runas -servicemanager -system_server -ueventd -zygote } selinuxfs:dir { open getattr read ioctl lock }; # search granted in domain
-auditallow { domain_deprecated -appdomain -debuggerd -init -installd -keystore -postinstall_dexopt -runas -servicemanager -system_server -ueventd -zygote } selinuxfs:file { open read ioctl lock }; # getattr granted in domain
+auditallow { domain_deprecated -appdomain -init -installd -keystore -postinstall_dexopt -runas -servicemanager -system_server -ueventd -zygote } selinuxfs:dir { open getattr read ioctl lock }; # search granted in domain
+auditallow { domain_deprecated -appdomain -init -installd -keystore -postinstall_dexopt -runas -servicemanager -system_server -ueventd -zygote } selinuxfs:file { open read ioctl lock }; # getattr granted in domain