[clang] [analyzer] Fix crash analyzing _BitInt() in evalIntegralCast (PR #65887)

[Björn Pettersson via cfe-commits]

bjope wrote:

I reverted this patch since buildbots have been complaining for almost an hour.
Here is the first failure mail I got:

```
The Buildbot has detected a failed build on builder clang-armv8-quick while building clang.

Full details are available at:
    https://lab.llvm.org/buildbot/#/builders/245/builds/14207

Worker for this Build: linaro-clang-armv8-quick

BUILD FAILED: failed 1 unexpected failures 38187 expected passes 71 expected failures 36091 unsupported tests (failure)

Step 5 (ninja check 1) failure: 1 unexpected failures 38187 expected passes 71 expected failures 36091 unsupported tests (failure)
******************** TEST 'Clang :: Analysis/bitint-no-crash.c' FAILED ********************
Script:
--
: 'RUN: at line 1';   /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/18/include -nostdsysteminc -analyze -analyzer-constraints=range -setup-static-analyzer -analyzer-checker=core    -analyzer-checker=debug.ExprInspection    -verify /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Analysis/bitint-no-crash.c
--
Exit Code: 1

Command Output (stderr):
--
error: 'expected-error' diagnostics seen but not expected: 
  File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Analysis/bitint-no-crash.c Line 7: signed _BitInt of bit sizes greater than 128 not supported
  File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Analysis/bitint-no-crash.c Line 8: signed _BitInt of bit sizes greater than 128 not supported
2 errors generated.

--
```

https://github.com/llvm/llvm-project/pull/65887