MINOR: configuration: File and line propagation

This patch permits to communicate file and line of the
configuration file at the configuration parser.
diff --git a/include/proto/sample.h b/include/proto/sample.h
index d78e82d..6b76662 100644
--- a/include/proto/sample.h
+++ b/include/proto/sample.h
@@ -28,7 +28,7 @@
 
 extern const char *smp_to_type[SMP_TYPES];
 
-struct sample_expr *sample_parse_expr(char **str, int *idx, char **err, struct arg_list *al);
+struct sample_expr *sample_parse_expr(char **str, int *idx, const char *file, int line, char **err, struct arg_list *al);
 struct sample_conv *find_sample_conv(const char *kw, int len);
 struct sample *sample_process(struct proxy *px, struct session *l4,
                                void *l7, unsigned int dir, struct sample_expr *expr,