Remove leading "00" byte from prime, if present

The primes in https://svn.nmap.org/nmap/scripts/ssl-dh-params.nse do not include a leading "00" byte, so don't include it in `$dh_p`.

testssl.sh

@@ -9392,7 +9392,9 @@ run_logjam() {
      if [[ -n "$key_bitstring" ]]; then
           dh_p="$($OPENSSL pkey -pubin -text -noout <<< "$key_bitstring" | awk '/prime:/,/generator:/' | tail -n +2 | head -n -1)"
           dh_p="$(strip_spaces "$(colon_to_spaces "$(newline_to_spaces "$dh_p")")")"
+          [[ "${dh_p:0:2}" == "00" ]] && dh_p="${dh_p:2}"
           # At this point the DH key's prime has been extracted into $dh_p. Compare is against known weak primes.
+          echo "dh_p = $dh_p"
      fi
 
      tmpfile_handle $FUNCNAME.txt