um: Fix VDSO compiler warning

Fix a warning about the function type being wrong.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/x86/um/vdso/um_vdso.c

@@ -47,7 +47,7 @@ time_t __vdso_time(time_t *t)
 
 	return secs;
 }
-int time(time_t *t) __attribute__((weak, alias("__vdso_time")));
+time_t time(time_t *t) __attribute__((weak, alias("__vdso_time")));
 
 long
 __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)