Default kits gets confused about gdb

Installing a new Qt SDK with the same settings that an older version created will mess up the Auto detected default kit: It will use the new name with the old configuration.

How to reproduce:

Start e.g. a creator from Qt 5.0.1 binary installer:

C:\Qt\Qt5.0.1-mingw\Tools\QtCreator\bin\qtcreator.exe -settingspath D:\dev\tmp\customsettings
close it

start now e.g. a 5.0.2 candidate:

C:\Qt\Qt5.0.2-455\Tools\QtCreator\bin\qtcreator.exe -settingspath D:\dev\tmp\customsettings

Check Kits tab. The default Kit is named "5.0.2", but actually uses the gdb from 5.0.1.