config/git: import suckless sbase

i currently use the output of sha512sum in several
places of xbmk, which is a bit unreliable in case
output changes.

other cases where i use util outputs in variables
are probably reliable, because i'm using mostly
posix utilities in those.

to mitigate this, i now import suckless sbase, which
has a reasonable sha512sum implementation.

*every* binary it builds is being placed in build.list,
because i'll probably start using more of them.

for example, i may start modifying the "date"
implementation, adding the GNU-specific options that
i need as mentioned on init.sh

i'm importing it in util/ because the sha512sum
util is needed for verifying project sources, so
if sbase itself is a "project source", that means
we can into a chicken and egg bootstrapping problem.

this is sbase at revision:
055cc1ae1b3a13c3d8f25af0a4a3316590efcd48

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/sbase/cp.1

@@ -0,0 +1,71 @@
+.Dd April 22, 2025
+.Dt CP 1
+.Os sbase
+.Sh NAME
+.Nm cp
+.Nd copy files and directories
+.Sh SYNOPSIS
+.Nm
+.Op Fl afipv
+.Oo
+.Fl R
+.Op Fl H | L | P
+.Oc
+.Ar source ...
+.Ar dest
+.Sh DESCRIPTION
+.Nm
+copies
+.Ar source
+to
+.Ar dest .
+If more than one
+.Ar source
+is given
+.Ar dest
+has to be a directory.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl a
+Preserve block devices, character devices, sockets and FIFOs.
+Implies
+.Fl p ,
+.Fl P
+and
+.Fl R .
+.It Fl f
+If an existing
+.Ar dest
+cannot be opened, remove it and try again.
+.It Fl i
+Interactive prompt before overwrite.
+.It Fl p
+Preserve mode, timestamp and permissions.
+.It Fl v
+Write "'source' -> 'dest'" for each
+.Ar source
+to stdout.
+.It Fl H
+Dereference
+.Ar source
+if it is a symbolic link.
+.It Fl L
+Dereference all symbolic links.
+This is the default without
+.Fl R .
+.It Fl P
+Preserve symbolic links.
+This is the default with
+.Fl R .
+.It Fl R
+Traverse directories recursively.
+If this flag is not specified, directories are not copied.
+.El
+.Sh SEE ALSO
+.Xr mv 1
+.Sh STANDARDS
+POSIX.1-2013.
+.Pp
+The
+.Op Fl av
+flags are an extension to that specification.