[MSAN][regression] compilation freezes with -fsanitize-memory-track-origins

Hello,

For the past few days, the MSAN compilation has been freezing on the following code. The last known working build was `Ubuntu clang version 22.0.0 (++20251113081817+83118de72238-1~exp1~20251113201939.1288)` from `https://apt.llvm.org/`.

`clang -c -fsanitize=memory -fsanitize-memory-track-origins -O2 c.c`

``` c
long stride;
int comb_c(unsigned char *a, unsigned char *b) {
int comb = 0;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 8; j++) {
comb += (((a[j] << 1) - b[j - stride] - b[j]) ^
((a[j] << 1) - b[j - stride] - b[j]) >> 31) -
(((a[j] << 1) - b[j - stride] - b[j]) >> 31) +
((((b[j] << 1) - a[j] - a[j + stride]) ^
((b[j] << 1) - a[j] - a[j + stride]) >> 31) -
(((b[j] << 1) - a[j] - a[j + stride]) >> 31));
}
a += stride;
b += stride;
}
return comb;
}
```

Thanks,
Kacper

Reproduce the freeze with the provided c.c reduction and the exact clang command, comparing it with the last known working Ubuntu clang build. Trace the MSAN compilation path for -fsanitize-memory-track-origins and confirm the command completes without freezing on the supplied code.

Written by the indexing model from the issue text.