This fixes the crash on with struct fields containing unknown types
reported on the forum:
https://sourceforge.net/p/cppcheck/discussion/general/thread/d64551cc55/#5f0f
The suggested patch doesn't handle the cases when there are struct
fields with arrays containing unknown types. So the addon will not
generate warnings in these cases. The problem is that Cppcheck doesn't
generate valueType-pointer information for unknown types in the dump
file. When adding this in symboldatabase.cpp, MISRA addon will generate
a lot of false positives because we depend on the null value of
valueType.
So I suppose it better to left this as is, to don't break the addon for
such rare cases.
79f59d8f39