Enabled -Wstrict-prototypes and fixed warnings.

include/jemalloc/internal/hook.h

@@ -144,7 +144,7 @@ struct hook_ralloc_args_s {
  * Returns an opaque handle to be used when removing the hook.  NULL means that
  * we couldn't install the hook.
  */
-bool hook_boot();
+bool hook_boot(void);
 
 void *hook_install(tsdn_t *tsdn, hooks_t *hooks);
 /* Uninstalls the hook with the handle previously returned from hook_install. */