When viewing a bug, make it possible to change its OS.

bug_form.pl

@@ -118,8 +118,10 @@ print "
     <TD><SELECT NAME=product>" .
     make_options(\@::legal_product, $bug{'product'}) .
     "</SELECT></TD>
-    <TD ALIGN=RIGHT><B>OS:</B></TD><TD>$bug{'op_sys'}</TD>
-    <TD ALIGN=RIGHT><B>Reporter:</B></TD><TD>$bug{'reporter'}</TD>
+    <TD ALIGN=RIGHT><B>OS:</B></TD>
+    <TD><SELECT NAME=op_sys>" .
+    make_options(\@::legal_opsys, $bug{'op_sys'}) .
+    "</SELECT><TD ALIGN=RIGHT><B>Reporter:</B></TD><TD>$bug{'reporter'}</TD>
   </TR><TR>
     <TD ALIGN=RIGHT><B><A HREF=\"bug_status.html\">Status:</A></B></TD>
       <TD>$bug{'bug_status'}</TD>

process_bug.cgi

@@ -122,7 +122,7 @@ sub ChangeResolution {
 
 foreach my $field ("rep_platform", "priority", "bug_severity", "url",
                    "summary", "component", "bug_file_loc", "short_desc",
-                   "product", "version", "component") {
+                   "product", "version", "component", "op_sys") {
     if (defined $::FORM{$field}) {
         if ($::FORM{$field} ne $::dontchange) {
             DoComma();