message: alloca fix to allow Clang with Microsoft CodeGen path
diff: #if !defined(alloca)
  #ifdef _WIN32
  #include <malloc.h> // alloca
  +#if !defined(alloca)
  +#define alloca _alloca // for clang with MS Codegen
  +#endif
  #elif defined(__GLIBC__) || defined(__sun)
  #include <alloca.h> // alloca
  #else
  