[llvm] [libomptarget] Add a test for OMP_TARGET_OFFLOAD=disabled (PR #146385)

[Michael Kruse via llvm-commits]

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@@ -0,0 +1,22 @@
+// RUN: %libomptarget-compile-generic
+// RUN:   env OMP_TARGET_OFFLOAD=disabled %libomptarget-run-generic 2>&1 |
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Meinersbur wrote:

Is nobody testing this? Fails unconditionally with
```sh
# shell parser error on RUN: at line 2: env OMP_TARGET_OFFLOAD=disabled /home/meinersbur/src/llvm/work/release/runtimes/runtimes-bins/offload/test/x86_64-unknown-linux-gnu-LTO/offloading/Output/disable_default_device.c.tmp 2>&1 |
```
`FileCheck %s` is missing

https://github.com/llvm/llvm-project/pull/146385