[clang] [SystemZ/[z/OS] Limit testcase to z/OS so we don't hit other platforms max limit (PR #210341)

[Abhina Sree via cfe-commits]

https://github.com/abhina-sree created https://github.com/llvm/llvm-project/pull/210341

This patch is to fix the error seen here:


```
******************** TEST 'Clang :: CodeGen/SystemZ/systemz-module.flags.c' FAILED ********************
Exit Code: 2
Command Output (stdout):
--
# RUN: at line 1
/home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/24/include -nostdsysteminc -source-date-epoch 253402300799 -triple s390x-ibm-zos -emit-llvm -o - /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/SystemZ/systemz-module.flags.c | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/SystemZ/systemz-module.flags.c
# executed command: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/24/include -nostdsysteminc -source-date-epoch 253402300799 -triple s390x-ibm-zos -emit-llvm -o - /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/SystemZ/systemz-module.flags.c
# .---command stderr------------
# | error: environment variable 'SOURCE_DATE_EPOCH' ('253402300799') must be a non-negative decimal integer <= 2147483647
# `-----------------------------
# error: command failed with exit status: 1
# executed command: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/SystemZ/systemz-module.flags.c
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/SystemZ/systemz-module.flags.c
# `-----------------------------
# error: command failed with exit status: 2
```

>From 74e12793910d3262c34c57942ed824684f6b221a Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Fri, 17 Jul 2026 10:03:17 -0400
Subject: [PATCH] limit testcase to z/OS so we don't hit other platforms max
 limit

---
 clang/test/CodeGen/SystemZ/systemz-module.flags.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/test/CodeGen/SystemZ/systemz-module.flags.c b/clang/test/CodeGen/SystemZ/systemz-module.flags.c
index 261dec81a4d52..c07d7443c5ada 100644
--- a/clang/test/CodeGen/SystemZ/systemz-module.flags.c
+++ b/clang/test/CodeGen/SystemZ/systemz-module.flags.c
@@ -1,3 +1,5 @@
 // RUN: %clang_cc1 -source-date-epoch 253402300799 -triple s390x-ibm-zos -emit-llvm -o - %s | FileCheck %s
 // CHECK: {{.*}}"zos_cu_language", !"C"}
 // CHECK: {{.*}}"zos_translation_time", i64 253402300799}
+
+// REQUIRES: system-zos