Fix: Enable MSVC build on Windows

[Leif-US]

This pull request fixes build failures on Windows when using the MSVC toolchain.
The build process previously failed due to two main issues:

1. A linker error caused by the use of the GCC/Clang-specific function __builtin_clz in lj92.c, which is not
   available in MSVC.
2. An unsupported compiler argument -std=gnu99 in setup.py, which is ignored by MSVC but indicates
   non-portable build logic.

These changes resolve the issues as follows:

• In src/pidng/liblj92/lj92.c: Replaces the compiler-specific function calls with a compatible MSVC
  implementation using the _BitScanReverse intrinsic. This ensures the code compiles correctly without linker
  errors.
• In setup.py: Removes the unsupported '-std=gnu99' compile argument to allow for a warning-free
  compilation on Windows.

With this patch, the package now installs successfully via pip on Windows.