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/linux/sched.h b/libc/kernel/uapi/linux/sched.h
index 13a34ce..b8f39dd 100644
--- a/libc/kernel/uapi/linux/sched.h
+++ b/libc/kernel/uapi/linux/sched.h
@@ -44,6 +44,7 @@
 #define CLONE_NEWPID 0x20000000
 #define CLONE_NEWNET 0x40000000
 #define CLONE_IO 0x80000000
+#define CLONE_CLEAR_SIGHAND 0x100000000ULL
 #ifndef __ASSEMBLY__
 struct clone_args {
   __aligned_u64 flags;
@@ -54,9 +55,12 @@
   __aligned_u64 stack;
   __aligned_u64 stack_size;
   __aligned_u64 tls;
+  __aligned_u64 set_tid;
+  __aligned_u64 set_tid_size;
 };
 #endif
 #define CLONE_ARGS_SIZE_VER0 64
+#define CLONE_ARGS_SIZE_VER1 80
 #define SCHED_NORMAL 0
 #define SCHED_FIFO 1
 #define SCHED_RR 2