Update to v5.5 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.5

Test: Boots on walleye.
Test: Ran bionic-unit-tests on walleye.
Test: Boots on cuttlefish.
Test: Ran bionic-unit-tests on cuttlefish.
Change-Id: I57387d3c31e0ba5ad125ffe291cecf365c7b374e
Merged-In: I57387d3c31e0ba5ad125ffe291cecf365c7b374e
diff --git a/libc/kernel/uapi/asm-arm64/asm/unistd.h b/libc/kernel/uapi/asm-arm64/asm/unistd.h
index 2f7a859..e93f3f1 100644
--- a/libc/kernel/uapi/asm-arm64/asm/unistd.h
+++ b/libc/kernel/uapi/asm-arm64/asm/unistd.h
@@ -20,4 +20,5 @@
 #define __ARCH_WANT_NEW_STAT
 #define __ARCH_WANT_SET_GET_RLIMIT
 #define __ARCH_WANT_TIME32_SYSCALLS
+#define __ARCH_WANT_SYS_CLONE3
 #include <asm-generic/unistd.h>