Fix error in ACE_Process_Options::inherit_environment ()

[viktor-ch]

While using ACE_Wide_To_Ascii string conversion class (and correspondingly ::WideCharToMultiByte) there must be expected that the length of the output multi-byte string is not equal to the length of the input Unicode string. That's why the variable iter used to iterate over the original Unicode environment variables must be increased by the source string length (and not by the length of the converted string).