Converts a binary OpenVMS format time expressing GMT (or the
    equivalent UTC) into a binary timestamp.
    Format
      #include <utc.h>
      int utc_mkvmsgmtime(*utc, *timadr)
         utc_t *utc;
         const long *timadr;
1 – Parameters
    Input
 *timadr
    Binary OpenVMS format time representing GMT or the UTC
    equivalent.
    Output
 *utc
    Binary timestamp.
2 – Description
    The Make VMS Greenwich Mean Time routine converts an OpenVMS
    format binary time representing GMT to a binary timestamp with
    the equivalent UTC value. Since the input and output values are
    based on different time standards, any input representing a value
    after A.D. 30,000 returns an error.
3 – Returns
     0   Indicates that the routine executed successfully.
    -1   Indicates an invalid time argument or invalid results.
4 – Example
See the sample program for the vmsgmtime routine.
5 – Related Functions
Function: utc_vmsgmtime