Converts a null-terminated character string that represents a
    relative timestamp to a binary timestamp.
    Format
      #include <utc.h>
      int utc_mkascreltime(*utc, *string)
         utc_t *utc;
         char *string;
1 – Parameters
    Input
 string
    A null-terminated string that expresses a relative timestamp in
    its ISO format.
    Output
 utc
    Resulting binary timestamp.
2 – Description
    The Make ASCII Relative Time routine converts a null-terminated
    string, which represents a relative timestamp, to a binary
    timestamp.
3 – Notes
The ASCII string must be null-terminated.
4 – Returns
     0   Indicates that the routine executed successfully.
    -1   Indicates an invalid time parameter or invalid results.
5 – Example
    The following example converts an ASCII relative time string to
    its binary equivalent.
    utc_t      utc;
    char       str[UTC_MAX_STR_LEN];
    /*
     * Relative time of 333 days, 12 hours, 1 minute, 37.223 seconds
     * Inaccuracy of 50.22 sec. in the format: -333-12:01:37.223I50.22
     */
    (void)strcpy((void *)str,
                 "-333-12:01:37.223I50.22");
    utc_mkascreltime(&utc,   /* Out: Binary utc               */
                     str);   /* In:  String                   */
6 – Related Functions
utc_ascreltime