util: Use qemu_getauxval in linux qemu_cache_utils_init

With this we no longer pass down envp, and thus all systems can have
the same void prototype.  So also eliminate a useless thunk.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
diff --git a/vl.c b/vl.c
index 0c9c359..e2c94bf 100644
--- a/vl.c
+++ b/vl.c
@@ -2895,7 +2895,7 @@
     rtc_clock = QEMU_CLOCK_HOST;
 
     qemu_init_auxval(envp);
-    qemu_cache_utils_init(envp);
+    qemu_cache_utils_init();
 
     QLIST_INIT (&vm_change_state_head);
     os_setup_early_signal_handling();