Debugger: Work around mis-reading of integral template types

Clang/LLDB toolchain issue: -1 gets recorded and read
as 'int' with value '0xffffffff'.

Change-Id: I070a83c282bc8a46efa011efb73f32cdbf46398c
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>