Debugger: Streamline gdb.Value field access workarounds

Change-Id: I1b3b81019f6861353e5ada350fadbe3c8734f186
Reviewed-by: hjk <hjk121@nokiamail.com>
Valgrind: Compile fix for Windows

Change-Id: Id60005f4760746299827fb502f1c0afec71542df
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@digia.com>