MINOR: vars: Make vars_(un|)set_by_name(_ifexist|) return a success value
Change the return type from `void` to `int` and return whether setting
the variable was successful.
diff --git a/include/proto/vars.h b/include/proto/vars.h
index caf00ff..81f99df 100644
--- a/include/proto/vars.h
+++ b/include/proto/vars.h
@@ -7,9 +7,9 @@
void vars_prune(struct vars *vars, struct session *sess, struct stream *strm);
void vars_prune_per_sess(struct vars *vars);
int vars_get_by_name(const char *name, size_t len, struct sample *smp);
-void vars_set_by_name_ifexist(const char *name, size_t len, struct sample *smp);
-void vars_set_by_name(const char *name, size_t len, struct sample *smp);
-void vars_unset_by_name_ifexist(const char *name, size_t len, struct sample *smp);
+int vars_set_by_name_ifexist(const char *name, size_t len, struct sample *smp);
+int vars_set_by_name(const char *name, size_t len, struct sample *smp);
+int vars_unset_by_name_ifexist(const char *name, size_t len, struct sample *smp);
int vars_get_by_desc(const struct var_desc *var_desc, struct sample *smp);
int vars_check_arg(struct arg *arg, char **err);