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/include/bits/glibc-syscalls.h b/libc/include/bits/glibc-syscalls.h
index 9b9a119..8c8e65c 100644
--- a/libc/include/bits/glibc-syscalls.h
+++ b/libc/include/bits/glibc-syscalls.h
@@ -801,6 +801,9 @@
 #if defined(__NR_process_madvise)
   #define SYS_process_madvise __NR_process_madvise
 #endif
+#if defined(__NR_process_mrelease)
+  #define SYS_process_mrelease __NR_process_mrelease
+#endif
 #if defined(__NR_process_vm_readv)
   #define SYS_process_vm_readv __NR_process_vm_readv
 #endif