[llvm] [SystemZ][z/OS] Add missing include header to AutoConvert.cpp to fix build (PR #84909)

[Fanbo Meng via llvm-commits]

https://github.com/fanbo-meng created https://github.com/llvm/llvm-project/pull/84909

https://github.com/llvm/llvm-project/commit/ba13fa2a5d57581bff1a7e9322234af30f4882f6 added usages of `errnoAsErrorCode()` to AutoConvert.cpp, need to include Error.h header to fix build failure.

>From d35189cfbb63595cc77573ba5bcb5e86e48c2960 Mon Sep 17 00:00:00 2001
From: Fanbo Meng <Fanbo.Meng at ibm.com>
Date: Tue, 12 Mar 2024 09:18:56 -0400
Subject: [PATCH] [SystemZ][z/OS] Add missing include header to AutoConvert.cpp
 to fix build

---
 llvm/lib/Support/AutoConvert.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/Support/AutoConvert.cpp b/llvm/lib/Support/AutoConvert.cpp
index 74842e9167bde5..c509284ee916ef 100644
--- a/llvm/lib/Support/AutoConvert.cpp
+++ b/llvm/lib/Support/AutoConvert.cpp
@@ -14,6 +14,7 @@
 #ifdef __MVS__
 
 #include "llvm/Support/AutoConvert.h"
+#include "llvm/Support/Error.h"
 #include <cassert>
 #include <fcntl.h>
 #include <sys/stat.h>