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/sha224sum.c

@@ -0,0 +1,45 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdint.h>
+#include <stdio.h>
+
+#include "crypt.h"
+#include "sha224.h"
+#include "util.h"
+
+static struct sha224 s;
+struct crypt_ops sha224_ops = {
+	sha224_init,
+	sha224_update,
+	sha224_sum,
+	&s,
+};
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-c] [file ...]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int ret = 0, (*cryptfunc)(int, char **, struct crypt_ops *, uint8_t *, size_t) = cryptmain;
+	uint8_t md[SHA224_DIGEST_LENGTH];
+
+	ARGBEGIN {
+	case 'b':
+	case 't':
+		/* ignore */
+		break;
+	case 'c':
+		cryptfunc = cryptcheck;
+		break;
+	default:
+		usage();
+	} ARGEND
+
+	ret |= cryptfunc(argc, argv, &sha224_ops, md, sizeof(md));
+	ret |= fshut(stdin, "<stdin>") | fshut(stdout, "<stdout>");
+
+	return ret;
+}