[mkgmap-dev] Commit r4893: code simplification (no functional change)

Version mkgmap-r4893 was committed by gerd on Fri, 04 Feb 2022 code simplification (no functional change) - add method readSectionInfo that also reads magic (extraValue) as 4 byte int - use it in some headers http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4893