libxl dirty in tree after libxl build

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Hello,

A build of libxl has just dirtied the tree with:

index 05f7ac74a0..94a4438666 100644
--- a/tools/libxl/libxlu_disk_l.c
+++ b/tools/libxl/libxlu_disk_l.c
@@ -10,221 +10,11 @@
 #define FLEX_SCANNER
 #define YY_FLEX_MAJOR_VERSION 2
 #define YY_FLEX_MINOR_VERSION 6
-#define YY_FLEX_SUBMINOR_VERSION 4
+#define YY_FLEX_SUBMINOR_VERSION 1
 #if YY_FLEX_SUBMINOR_VERSION > 0
 #define FLEX_BETA
 #endif

and a whole slew of other changes in the generated code.  It looks like
the version of Flex has just been updated in Jessie.

Given the flex and bison are strictly required for the libxl build, why
is this temporary file checked in?

~Andrew