fmt_asn1dertag - encode unsigned integer like ASN.1 DER tag

       fmt_asn1dertag encodes an unsigned integer using the ASN.1 DER for encoding tag.  This takes one byte for
       every 7 bits in the number.

       If dest equals FMT_LEN (i.e. is NULL), fmt_asn1dertag returns the number of bytes it would have written.

       For  convenience,  fmt.h  defines  the  integer  FMT_ASN1TAG  to  be big enough to contain every possible
       fmt_asn1dertag output.

       fmt_asn1dertag - encode unsigned integer like ASN.1 DER tag

scan_asn1dertag(3)

                                                                                               fmt_asn1dertag(3)

#include<libowfat/fmt.h>

       size_t fmt_asn1dertag(char *dest,unsigned long long source);