[clang] [compiler-rt] [ubsan] Display correct runtime messages for negative _BitInt (PR #96240)

[Thurston Dang via cfe-commits]

thurstond wrote:

One of the tests is failing:
```
compiler-rt/test/ubsan/TestCases/Integer/bit-int-pass.c:31:15: error: CHECK-NOT: excluded string found in input
// CHECK-NOT: runtime error:
              ^
<stdin>:1:110: note: found here
compiler-rt/test/ubsan/TestCases/Integer/bit-int-pass.c:11:10: runtime error: implicit conversion from type '_BitInt(37)' of value 60129542145 (64-bit, signed) to type 'uint32_t' (aka 'unsigned int') changed the value to 1 (32-bit, unsigned)
                                                                                                             ^~~~~~~~~~~~~~
```

https://github.com/llvm/llvm-project/pull/96240