Include inside namespace leads to undefined functions

[jjochum]

https://github.com/dascandy/hippomocks/blob/10960d027b398444ec3ec6ce2487de3db0283ff8/HippoMocks/hippomocks.h#L233

These includes should probably be outside of the namespace definition. In case a class uses one of the functions defined in sys/mman.h, this function is then undefined for the class.