MAINTAINERS, get_maintainer.pl: Add Designated Reviewer (R:) role

The syntax has been copied from the Linux Maintainers file. I moved the following Linux
get_maintainer.pl patches to Xen, fixing up some merge issues (and a bug).

The get_maintainer.pl changes were based on the following git commits
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/scripts/get_maintainer.pl?id=
* c1c3f2c906e35bcb6e4cdf5b8e077660fead14fe
* 4f07510df2e8c47fd65b8ffaaf6c5d334d59d598

I also removed code related to
  P: Person (obsolete)
which is in the Linux MAINTAINER's file, but not ours. I may not have
caught all instances though.

I have tested on a number of files using mock entries in MAINTAINERS
using ./scripts/get_maintainer.pl -f ...

I also tested --nor to disable the support and it worked as expected.

Cc: Lars Kurth <lars.kurth@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Julien Grall <julien.grall@arm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Juergen Gross <jgross@suse.com>
Signed-off-by: Lars Kurth <lars.kurth@citrix.com>

Release-acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

MAINTAINERS

@@ -60,6 +60,10 @@ appropriate branch.
 Descriptions of section entries:
 
 	M: Mail patches to: FullName <address@domain>
+	R: Designated reviewer: FullName <address@domain>
+	   Reviewers should be CCed on patches.  However, they do not
+	   have a formal governance role, and are listed here
+	   simply because of their own request.
 	L: Mailing list that is relevant to this area
 	W: Web-page with status/info
 	T: SCM tree type and location.  Type is one of: git, hg, quilt, stgit.

scripts/get_maintainer.pl

@@ -21,6 +21,7 @@ my $xen_path = "./";
 my $email = 1;
 my $email_usename = 1;
 my $email_maintainer = 1;
+my $email_reviewer = 1;
 my $email_list = 1;
 my $email_subscriber_list = 0;
 my $email_git_penguin_chiefs = 0;
@@ -199,6 +200,7 @@ if (!GetOptions(
 		'mailmap!' => \$email_use_mailmap,
 		'drop_the_rest_supporter!' => \$email_drop_the_rest_supporter_if_supporter_found,
 		'm!' => \$email_maintainer,
+		'r!' => \$email_reviewer,
 		'n!' => \$email_usename,
 		'l!' => \$email_list,
 		's!' => \$email_subscriber_list,
@@ -257,7 +259,8 @@ if ($sections) {
 }
 
 if ($email &&
-    ($email_maintainer + $email_list + $email_subscriber_list +
+    ($email_maintainer + $email_reviewer +
+     $email_list + $email_subscriber_list +
      $email_git + $email_git_penguin_chiefs + $email_git_blame) == 0) {
     die "$P: Please select at least 1 email option\n";
 }
@@ -791,6 +794,7 @@ MAINTAINER field selection options:
     --hg-since => hg history to use (default: $email_hg_since)
     --interactive => display a menu (mostly useful if used with the --git option)
     --m => include maintainer(s) if any
+    --r => include reviewer(s) if any
     --n => include name 'Full Name <addr\@domain.tld>'
     --l => include list(s) if any
     --s => include subscriber only list(s) if any
@@ -817,7 +821,7 @@ Other options:
   --help => show this help information
 
 Default options:
-  [--email --nogit --git-fallback --m --n --l --multiline -pattern-depth=0
+  [--email --nogit --git-fallback --m --r --n --l --multiline -pattern-depth=0
    --remove-duplicates --rolestats]
 
 Notes:
@@ -1080,21 +1084,15 @@ sub add_categories {
 		}
 	    } elsif ($ptype eq "M") {
 		my ($name, $address) = parse_email($pvalue);
-		if ($name eq "") {
-		    if ($i > 0) {
-			my $tv = $typevalue[$i - 1];
-			if ($tv =~ m/^([A-Z]):\s*(.*)/) {
-			    if ($1 eq "P") {
-				$name = $2;
-				$pvalue = format_email($name, $address, $email_usename);
-			    }
-			}
-		    }
-		}
 		if ($email_maintainer) {
 		    my $role = get_maintainer_role($i);
 		    push_email_addresses($pvalue, $role);
 		}
+	    } elsif ($ptype eq "R") {
+		my ($name, $address) = parse_email($pvalue);
+		if ($email_reviewer) {
+		    push_email_addresses($pvalue, 'reviewer');
+		}
 	    } elsif ($ptype eq "T") {
 		push(@scm, $pvalue);
 	    } elsif ($ptype eq "W") {