Modify valgrind's configure script to accept linux-libre-4.x as being in the
same family as 3.x.

--- valgrind-3.10.1/configure	2015-09-15 18:02:20.710262686 -0400
+++ valgrind-3.10.1/configure	2015-09-15 18:02:59.831829731 -0400
@@ -5553,9 +5553,9 @@
         kernel=`uname -r`
 
         case "${kernel}" in
-             2.6.*|3.*)
-        	    { $as_echo "$as_me:${as_lineno-$LINENO}: result: 2.6.x/3.x family (${kernel})" >&5
-$as_echo "2.6.x/3.x family (${kernel})" >&6; }
+             2.6.*|3.*|4.*)
+        	    { $as_echo "$as_me:${as_lineno-$LINENO}: result: 2.6.x/3.x/4.x family (${kernel})" >&5
+$as_echo "2.6.x/3.x/4.x family (${kernel})" >&6; }
 
 $as_echo "#define KERNEL_2_6 1" >>confdefs.h