[clang] [clang] consistently quote expressions in diagnostics (PR #134769)

[Younan Zhang via cfe-commits]

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@@ -18,19 +18,19 @@ int D = 1;
 #pragma data_seg(".data")
 int a = 1;
 extern const Mutable mutable_custom_section;
-const Mutable mutable_custom_section; // expected-warning {{`#pragma const_seg` for section ".my_const" will not apply to 'mutable_custom_section' due to the presence of a mutable field}}
+const Mutable mutable_custom_section; // expected-warning {{`#pragma const_seg` for section '".my_const"' will not apply to 'mutable_custom_section' due to the presence of a mutable field}}
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zyn0217 wrote:

This looks suspicious. Is `'"` what we want?

https://github.com/llvm/llvm-project/pull/134769