Fix 32 bit os issue with argument parsing (strtol -> strtoll)

This pull request removes an error on x86 operating systems when using the C driver and parsing timestamps.

Timestamps are defined 64 bits long.
On x86_64 strtol and strtoll both returns 64 bits integers.
On x86 strtoll returns 64 bits integer while strtol returns 32 bits integer.

Therefore using strtoll rather than strtol for compliance.