[clang] [Sema] Add check for bitfield assignments to larger integral types (PR #68276)

[Aaron Ballman via cfe-commits]

================
@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -Wconversion -fsyntax-only -verify %s
+// RUN: %clang_cc1 -Wbitfield-conversion -fsyntax-only -verify %s
+
+typedef struct _xx {
+     int bf:9; // expected-note{{declared here}}
+     // expected-note at -1{{declared here}}
+     // expected-note at -2{{declared here}}
+     // expected-note at -3{{declared here}}
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AaronBallman wrote:

```suggestion
     int bf:9; // expected-note 4{{declared here}}
```
NFC, but is shorter

https://github.com/llvm/llvm-project/pull/68276