krb5 defines `strtok_r` for Windows unconditionally in its public
header:
dc5554394e/src/include/win-mac.h (L214-L215)
resulting in this warning:
```
lib\strtok.h(31,9): warning C4005: 'strtok_r': macro redefinition
C:\vcpkg\installed\x64-windows\include\win-mac.h(215,9):
see previous definition of 'strtok_r'
```
The krb5 macro collides with curl's internal definition, in case
the `strtok_r` function is undetected and falling back to a local
replacement.
Reported-by: Tal Regev
Bug: https://github.com/curl/curl/pull/15549#issuecomment-2468251761Closes#15564
22c45844af