Pass ‘struct pkginfoperfile’ from maint script functions to do_script

This allows us to retrieve package information from either the installed
package or the one being installed from the maintainer script invoking
functions.

src/help.c

@@ -247,7 +247,7 @@ static void setexecute(const char *path, struct stat *stab) {
 }
 
 static int
-do_script(struct pkginfo *pkg,
+do_script(struct pkginfo *pkg, struct pkginfoperfile *pif,
           const char *scriptname, const char *scriptpath, struct stat *stab,
           char *const arglist[], const char *desc, const char *name, int warn)
 {
@@ -302,7 +302,8 @@ vmaintainer_script_installed(struct pkginfo *pkg, const char *scriptname,
     }
     ohshite(_("unable to stat %s `%.250s'"), buf, scriptpath);
   }
-  do_script(pkg, scriptname, scriptpath, &stab, arglist, _("unable to execute %s"), buf, 0);
+  do_script(pkg, &pkg->installed, scriptname, scriptpath, &stab,
+            arglist, _("unable to execute %s"), buf, 0);
 
   return 1;
 }
@@ -362,8 +363,8 @@ maintainer_script_new(struct pkginfo *pkg,
     }
     ohshite(_("unable to stat %s `%.250s'"), buf, cidir);
   }
-  do_script(pkg, scriptname, cidir, &stab, arglist,
-            _("unable to execute %s"), buf, 0);
+  do_script(pkg, &pkg->available, scriptname, cidir, &stab,
+            arglist, _("unable to execute %s"), buf, 0);
   post_script_tasks();
 
   return 1;
@@ -393,8 +394,8 @@ int maintainer_script_alternative(struct pkginfo *pkg,
     warning(_("unable to stat %s '%.250s': %s"),
             buf,oldscriptpath,strerror(errno));
   } else {
-    if (!do_script(pkg, scriptname, oldscriptpath, &stab, arglist,
-                   _("unable to execute %s"), buf, PROCWARN)) {
+    if (!do_script(pkg, &pkg->installed, scriptname, oldscriptpath, &stab,
+                   arglist, _("unable to execute %s"), buf, PROCWARN)) {
       post_script_tasks();
       return 1;
     }
@@ -415,7 +416,8 @@ int maintainer_script_alternative(struct pkginfo *pkg,
       ohshite(_("unable to stat %s `%.250s'"),buf,cidir);
   }
 
-  do_script(pkg, scriptname, cidir, &stab, arglist, _("unable to execute %s"), buf, 0);
+  do_script(pkg, &pkg->available, scriptname, cidir, &stab,
+            arglist, _("unable to execute %s"), buf, 0);
   fprintf(stderr, _("dpkg: ... it looks like that went OK.\n"));
 
   post_script_tasks();