gcc 5.4.0 auto iterator with maps

[john30]

this is an issue to keep track of the original one posted in ebusd-configuration. There seems to be an issue with gcc version 5.4.0 that does not exist in 5.4.1 (at least on amd64); When using an auto iterator on a std::map, a char* variable in the same scope gets reset to length 0 on first entry of the loop. The issue https://github.com/john30/ebusd-configuration/issues/69 was resolved with commit 77d2a80 by doing the iteration in the traditional way using map.begin/end.