Fix string issue with minidumps
Fix string issue with minidumps

In minidumps we had an issue where string offset fields would be found
but they could not actually get values.

kailer89/clrmd,cshung/clrmd,jazzdelightsme/clrmd,JeffCyr/clrmd,larrynung/clrmd,stjeong/clrmd,tomasr/clrmd,stefangossner/clrmd,Microsoft/clrmd,cshung/clrmd,Microsoft/clrmd