dpkg: Add invoke hooks for add-architecture and remove-architecture

Prompted-by: Helmut Grohne <helmut@subdivi.de>

debian/changelog

@@ -9,6 +9,8 @@ dpkg (1.17.19) UNRELEASED; urgency=low
     Regression introduced in dpkg 1.17.14. Closes: #765110
   * Add new --remove-pidfile option to start-stop-daemon.
   * Mention --pid and --ppid in start-stop-daemon(8) man page DESCRIPTION.
+  * Add invoke hooks for dpkg --add-architecture and --remove-architecture.
+    Prompted by Helmut Grohne <helmut@subdivi.de>.
 
   [ Updated programs translations ]
   * Italian (Milo Casagrande): Closes: #765748

man/dpkg.1

@@ -615,7 +615,8 @@ installed.
 .BI \-\-post\-invoke= command
 Set an invoke hook \fIcommand\fP to be run via \*(lqsh \-c\*(rq before or
 after the \fBdpkg\fP run for the \fIunpack\fP, \fIconfigure\fP, \fIinstall\fP,
-\fItriggers\-only\fP, \fIremove\fP and \fIpurge\fP \fBdpkg\fP actions. This
+\fItriggers\-only\fP, \fIremove\fP, \fIpurge\fP, \fIadd\-architecture\fP and
+\fIremove\-architecture\fP \fBdpkg\fP actions. This
 option can be specified multiple times. The order the options are specified
 is preserved, with the ones from the configuration files taking precedence.
 The environment variable \fBDPKG_HOOK_ACTION\fP is set for the hooks to the

src/main.c

@@ -419,6 +419,8 @@ is_invoke_action(enum action action)
   case act_triggers:
   case act_remove:
   case act_purge:
+  case act_arch_add:
+  case act_arch_remove:
     return true;
   default:
     return false;