strtoul in bif.l corrupts numbers larger than 2^32 on Windows

[PaulTNA]

On line 277 of bif.l, strtoul is used to convert the value from a string to uint64_t.
However on Windows, unsigned long is 32 bits not 64, so strtoul will silently corrupt any value greater than 0xFFFFFFFF to that value.

The correct function should be strtoull