Add patch header to alpha fix based on the bug report it came from

svn path=/dists/sid/linux/; revision=20021

debian/patches/bugfix/alpha/alpha-use-large-data-model.diff

@@ -1,3 +1,17 @@
+From: Michael Cree <mcree@orcon.net.nz>
+Subject: alpha: Use large data model
+Date: Sun, 26 Aug 2012 15:01:24 +1200
+Bug-Debian: http://bugs.debian.org/685894
+
+We will have to move to the default compiler (gcc-4.6) but using gcc-4.6
+to build the kernel results in relocation errors against the sbss
+section during the link.  This can be worked around by modifying the
+-msmall-data compiler argument in arch/alpha/Makefile to -mlarge-data.
+It means extra CPU instructions to access kernel global variables thus a
+slightly larger and less efficient kernel.  I did try to ask the gcc
+Alpha maintainer why using gcc-4.6 should have such an effect but did
+not get back a particularly informative answer.
+
 diff --git a/arch/alpha/Makefile b/arch/alpha/Makefile
 index 4759fe7..b5d44bd 100644
 --- a/arch/alpha/Makefile