[clang] [driver] Only check for unused plugin options (PR #91522)

[Hubert Tong via cfe-commits]

================
@@ -23,5 +23,5 @@
 
 // Plugins are only relevant for the -cc1 phase. No warning should be raised
 // when only using the assembler. See GH #88173.
-// RUN: %clang -c -fpass-plugin=bar.so -fplugin=bar.so -fplugin-arg-bar-option -Werror -x assembler %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-PLUGIN-ASM
-// CHECK-PLUGIN-ASM-NOT: argument unused during compilation
+// RUN: %clang -c -fpass-plugin=bar.so -fplugin=bar.so -fplugin-arg-bar-option -Wunused-command-line-argument -x assembler %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-PLUGIN-ASM
+// CHECK-PLUGIN-ASM-NOT: argument unused during compilation: '-f{{[a-z-]*-plugin[^']*}}'
----------------
hubert-reinterpretcast wrote:

Sorry for my mistake "offline"; we want to catch `-fplugin*` too:
```suggestion
// CHECK-PLUGIN-ASM-NOT: argument unused during compilation: '-f{{[a-z-]*plugin[^']*}}'
```

https://github.com/llvm/llvm-project/pull/91522