Also fix check with old (~4.2) gcc

So that the headers can be used from a C++ program.

Compliant with EMMG<->MUX interface defined in ETSI TS 103 197 V1.3.1 (2003-01)

Without this patch I am getting the iconv_open() errors on uclibc.

(spotted by Coverity: CID 1109722)

(spotted by Coverity: CID 1109725)

Version is 5 bits instead of 4 bits, as reported by Sebastien (Coexsi).

(thanks Kieran!)

I have been looking at implementing support for parsing the LCN
descriptor for UK DVB-T and to my supprise most of it was already there
but for a different standard. In the D-Book LCN is tag 0x83 with private
data specifier of 0x233a where as what is currently implented is the
IEC/CENELEC 62 216 standard where the only difference (in the actual
data) is the latter has 1 bit that specifies if the channel is vissible
or not and the private data specifier is 0x0028.

A marker bit is missing when both PTS and DTS are present. The syntax was
therefore invalid.