isnan报错

Nobody has claimed this yet.

```
In file included from /home/xxx/ClionProjects/InferLLM/src/kern/optimized/x86/quantize.h:3:0,
from /home/xxx/ClionProjects/InferLLM/src/kern/optimized/kernel_opt.cpp:11:
/home/xxx/ClionProjects/InferLLM/src/kern/optimized/x86/quantize.h: In function ‘void inferllm::opt::dequantize_row_q4_0(const void*, float*, int)’:
/home/xxx/ClionProjects/InferLLM/src/kern/optimized/x86/quantize.h:260:46: error: ‘isnan’ was not declared in this scope
assert(!isnan(y[i * QK40 + l + 0]));
^
/home/xxx/ClionProjects/InferLLM/src/kern/optimized/x86/quantize.h:260:46: note: suggested alternative:
In file included from /usr/include/c++/5/random:38:0,
from /home/xxx/ClionProjects/InferLLM/src/utils.h:8,
from /home/xxx/ClionProjects/InferLLM/src/kern/optimized/kernel_opt.cpp:3:
/usr/include/c++/5/cmath:641:5: note: ‘std::isnan’
isnan(_Tp __x)
^
CMakeFiles/InferLLMShared.dir/build.make:257: recipe for target 'CMakeFiles/InferLLMShared.dir/src/kern/optimized/kernel_opt.cpp.o' failed
make[2]: *** [CMakeFiles/InferLLMShared.dir/src/kern/optimized/kernel_opt.cpp.o] Error 1
CMakeFiles/Makefile2:90: recipe for target 'CMakeFiles/InferLLMShared.dir/all' failed
make[1]: *** [CMakeFiles/InferLLMShared.dir/all] Error 2
Makefile:90: recipe for target 'all' failed
make: *** [all] Error 2
```

Start with src/kern/optimized/x86/quantize.h around line 260, where the build reports that isnan is not declared. Reproduce the failure with the repository's CMake build and inspect the nearby includes and namespace usage. Done means the InferLLMShared target builds successfully without this error.

Written by the indexing model from the issue text.