xdl_diff: identify call sites.

This inserts a new function xdi_diff() that currently does not
do anything other than calling the underlying xdl_diff() to the
callchain of current callers of xdl_diff() function.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

xdiff-interface.c

@@ -103,6 +103,11 @@ int xdiff_outf(void *priv_, mmbuffer_t *mb, int nbuf)
 	return 0;
 }
 
+int xdi_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, xdemitconf_t const *xecfg, xdemitcb_t *xecb)
+{
+	return xdl_diff(mf1, mf2, xpp, xecfg, xecb);
+}
+
 int read_mmfile(mmfile_t *ptr, const char *filename)
 {
 	struct stat st;