CUDA compilation fails with __builtin_is_constant_evaluated in boost/core/bit.hpp

**Description**:
- Boost Version: 1.89.0
- CUDA Version: 12.6
- MSVC Version: 2022 (1925+)
- Error: "variable in constexpr function is uninitialized" for unsigned long r;

**Root Cause**:
Line 35 enables BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL for MSVC 1925+ but doesn't exclude CUDA compiler (nvcc), which has stricter constexpr requirements.

**Proposed Fix**:
Change line 42 from:
#if defined(BOOST_MSVC) && BOOST_MSVC >= 1925
to:
#if defined(BOOST_MSVC) && BOOST_MSVC >= 1925 && '!defined(\_\_CUDACC\_\_)'

**Impact**: Prevents CUDA compilation errors while maintaining optimization for regular MSVC builds.