Update to v5.15 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.15

Test: Builds, and ran bionic unit tests on flame.
Change-Id: I86901ea6d89fb0f7384b90a47bef35d194083c24
diff --git a/libc/kernel/uapi/linux/mempolicy.h b/libc/kernel/uapi/linux/mempolicy.h
index 4f8c02f..f92970f 100644
--- a/libc/kernel/uapi/linux/mempolicy.h
+++ b/libc/kernel/uapi/linux/mempolicy.h
@@ -25,6 +25,7 @@
   MPOL_BIND,
   MPOL_INTERLEAVE,
   MPOL_LOCAL,
+  MPOL_PREFERRED_MANY,
   MPOL_MAX,
 };
 #define MPOL_F_STATIC_NODES (1 << 15)