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/tail.1

@@ -0,0 +1,51 @@
+.Dd October 8, 2015
+.Dt TAIL 1
+.Os sbase
+.Sh NAME
+.Nm tail
+.Nd display final lines of files
+.Sh SYNOPSIS
+.Nm
+.Op Fl f
+.Op Fl c Ar num | Fl m Ar num | Fl n Ar num | Fl Ns Ar num
+.Op Ar file ...
+.Sh DESCRIPTION
+.Nm
+writes the last 10 lines of each
+.Ar file
+to stdout.
+If no
+.Ar file
+is given,
+.Nm
+reads from stdin.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl c Ar num | Fl m Ar num | Fl n Ar num | Fl Ns Ar num
+Display final
+.Ar num
+bytes | characters | lines | lines.
+If
+.Ar num
+begins with '+'
+it is an offset from the beginning of each
+.Ar file .
+If
+.Ar num
+begins with '-' it is as if no sign was given.
+The default is 10 lines.
+.It Fl f
+If one
+.Ar file
+is specified, append lines to output as
+.Ar file
+grows.
+.El
+.Sh SEE ALSO
+.Xr head 1
+.Sh STANDARDS
+POSIX.1-2013.
+.Pp
+The
+.Op Fl Ns Ar num
+syntax is an extension to that specification.