argo: port to 4.19 kernel

[cjp256]

Currently untested, but builds. Also needs following kernel patch to restore hypercall5:

From 2fa28193c62aa573bb309c0e58c884c248962b36 Mon Sep 17 00:00:00 2001
From: Chris Patterson <pattersonc@ainfosec.com>
Date: Fri, 25 Jan 2019 14:53:11 -0500
Subject: [PATCH] xen: re-add hypercall5 macro, used by argo

Signed-off-by: Chris Patterson <pattersonc@ainfosec.com>
---
 arch/x86/include/asm/xen/hypercall.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index ef05bea7010d..efabee330907 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -197,6 +197,18 @@ extern struct { char _entry[32]; } hypercall_page[];
 	(type)__res;							\
 })
 
+#define _hypercall5(type, name, a1, a2, a3, a4, a5)                    \
+({                                                                     \
+       __HYPERCALL_DECLS;                                              \
+       __HYPERCALL_5ARG(a1, a2, a3, a4, a5);                           \
+       asm volatile (__HYPERCALL                                       \
+                     : __HYPERCALL_5PARAM                              \
+                     : __HYPERCALL_ENTRY(name)                         \
+                     : __HYPERCALL_CLOBBER5);                          \
+       (type)__res;                                                    \
+})
+
+
 static inline long
 xen_single_call(unsigned int call,
 		unsigned long a1, unsigned long a2,
-- 
2.17.1