When WIN32 is undefined an unreachable code warning was generated
since "/bin/sh" is returned as the default resposne.
Change-Id: I757c9d05db62c1d52fee0e510259098d73273a84
We add roken_get_{shell, username, appdatadir, homedir}() functions. These use
a combination of secure_getenv(), getpwuid_r(), getlogin_r(), or various WIN32
functions to get this information.
Use roken_get_appdatadir() instead of roken_get_homedir() when looking for
dotfiles.