Nullability correction for stdlib module.

Bugs: b/245972273
Test: adb shell
Change-Id: I0a800ccfe3bae88d3e924dd621bad182cb186b27
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index b416f62..2bcb870 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -91,7 +91,7 @@
 
 void* _Nullable bsearch(const void* _Nonnull __key, const void* _Nullable __base, size_t __nmemb, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull __lhs, const void* _Nonnull __rhs));
 
-void qsort(void* _Nullable __base, size_t __nmemb, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull __lhs, const void* _Nonnull __rhs));
+void qsort(void* _Nullable __base, size_t __nmemb, size_t __size, int (* _Nonnull __comparator)(const void* _Nullable __lhs, const void* _Nullable __rhs));
 
 uint32_t arc4random(void);
 uint32_t arc4random_uniform(uint32_t __upper_bound);