mailinfo: cleanup extra spaces for complex 'From:'

currently for cases like

    From: A U Thor <a.u.thor@example.com> (Comment)

mailinfo extracts the following 'Author:' field:

    Author: A U Thor   (Comment)
                     ^^
which has two extra spaces left in there after removed email part.

I think this is wrong so here is a fix.

Signed-off-by: Kirill Smelkov <kirr@landau.phys.spbu.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5100/info0001

@@ -1,4 +1,4 @@
-Author: A U Thor
+Author: A (zzz) U Thor (Comment)
 Email: a.u.thor@example.com
 Subject: a commit.
 Date: Fri, 9 Jun 2006 00:44:16 -0700

t/t5100/rfc2047-info-0004

@@ -1,4 +1,4 @@
-Author: Nathaniel Borenstein   (םולש ןב ילטפנ)
+Author: Nathaniel Borenstein (םולש ןב ילטפנ)
 Email: nsb@thumper.bellcore.com
 Subject: Test of new header generator
 

t/t5100/sample.mbox

@@ -2,10 +2,10 @@
 	
     
 From nobody Mon Sep 17 00:00:00 2001
-From: A
+From: A (zzz)
       U
       Thor
-      <a.u.thor@example.com>
+      <a.u.thor@example.com> (Comment)
 Date: Fri, 9 Jun 2006 00:44:16 -0700
 Subject: [PATCH] a commit.