[clang] [flang] [clang][driver] Special care for -l flags in config files (PR #117573)

[Fangrui Song via cfe-commits]

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@@ -82,3 +82,35 @@
 // CHECK-TWO-CONFIGS: -isysroot
 // CHECK-TWO-CONFIGS-SAME: /opt/data
 // CHECK-TWO-CONFIGS-SAME: -Wall
+
+//--- The linker input flags should be moved to the end of input list and appear only when linking.
+// RUN: %clang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -o %s.out %s -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING
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MaskRay wrote:

`-o %s.out` is strange. We typically use `-o %t` for output. That said, since we use -### and the output isn't useful, just omit it.

https://github.com/llvm/llvm-project/pull/117573