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/mktemp.1

@@ -0,0 +1,50 @@
+.Dd October 8, 2015
+.Dt MKTEMP 1
+.Os sbase
+.Sh NAME
+.Nm mktemp
+.Nd create temporary file or directory
+.Sh SYNOPSIS
+.Nm
+.Op Fl dqtu
+.Op Fl p Ar directory
+.Op Ar template
+.Sh DESCRIPTION
+.Nm
+creates a temporary file by generating a unique filename with
+.Ar template ,
+which has to have at least six 'X's appended to it.
+If no
+.Ar template
+is specified, a default of 'tmp.XXXXXXXXXX' is used and the
+tmpdir set to '/tmp' or, if set, the TMPDIR environment variable.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl d
+Create a temporary directory instead of a file.
+.It Fl p Ar directory
+Use the specified
+.Ar directory
+as a prefix when generating the temporary filename.
+The directory will be overridden by the user's
+.Ev TMPDIR
+environment variable if it is set.
+This option implies the
+.Fl t
+flag (see below).
+.It Fl q
+Fail silently if an error occurs.
+.It Fl t
+Generate a path rooted in a temporary directory.
+.It Fl u
+Unlink file before
+.Nm
+exits.
+This is slightly better than
+.Xr mktemp 3
+but still introduces a race condition.
+Use of this option is not encouraged.
+.El
+.Sh SEE ALSO
+.Xr mkdtemp 3 ,
+.Xr mkstemp 3