Previously, the POSIX shell utilities were intermixed with the
POSIX API implementation.
The POSIX shell utilities only depend on the public POSIX API,
so it makes sense to keep them in a separate subdirectory.
Signed-off-by: Christopher Friedt <cfriedt@meta.com>
This change is setting up for switching over to proper POSIX
option requirements, feature test macros, and a dependency
structure that is reflective of the standard.
Signed-off-by: Christopher Friedt <cfriedt@meta.com>