[PATCH]: linux-2.6: use string operators instead of numeric ones for string concatenation

["Stefan Lippers-Hollmann" <s.L-H@gmx.de>]

Revision 16224 of svn://svn.debian.org/svn/kernel/dists/trunk/linux-2.6 
enabled "use strict;" and "use warnings;" for the perl based maintainer 
scripts of linux-image-@upstreamversion@@abiname@@localversion@, this in 
turn exposed that the numeric '+=' operator is used to concatenate 
$message and $dir_message variables; this patch fixes this by using the 
string operator '.='.

Argument "Module sub-directories were detected.\n" isn't numeric in addition (+) at /var/lib/dpkg/tmp.ci/preinst line 100.
Argument "" isn't numeric in addition (+) at /var/lib/dpkg/tmp.ci/preinst line 100.

Signed-off-by: Stefan Lippers-Hollmann <s.l-h@gmx.de>
---

 debian/templates/temp.image.plain/preinst |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff -Nrup a/debian/templates/temp.image.plain/preinst b/debian/templates/temp.image.plain/preinst
--- a/debian/templates/temp.image.plain/preinst
+++ b/debian/templates/temp.image.plain/preinst
@@ -97,7 +97,7 @@ sub check {
               unless $dir_message;
           }
         }
-        $message += $dir_message if $dir_message;
+        $message .= $dir_message if $dir_message;
       }
 
       my @links = grep { -l "$lib_modules/$_" } @children;
@@ -108,10 +108,10 @@ sub check {
           next if ($link =~ /^source$/);
           $links_message = "Symbolic links were detected in $modules_base/$version.\n";
         }
-        $message += $links_message if $links_message;
+        $message .= $links_message if $links_message;
       }
       my @files = grep { -f "$lib_modules/$_" } @children;
-      $message += "Additional files also exist in $modules_base/$version.\n"
+      $message .= "Additional files also exist in $modules_base/$version.\n"
         if ($#files > -1);
     }
   }