switch spkmodem_decode back to spkmodem_recv

this version is more tested. i'll merge _decode back
once it's better tested. it contains a lot of invasive
changes, whereas recv is much closer to the original GNU
code that i inherited, that i also know works quite well.

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

util/spkmodem_recv/Makefile

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+CC?=cc
+CFLAGS?=-Os -Wall -Wextra -Werror -pedantic
+DESTDIR?=
+PREFIX?=/usr/local
+INSTALL?=install
+
+spkmodem-recv:
+	$(CC) $(CFLAGS) -o $@ $@.c
+install: spkmodem-recv
+	$(INSTALL) -d $(DESTDIR)$(PREFIX)/bin/
+	$(INSTALL) $< -t $(DESTDIR)$(PREFIX)/bin/
+clean:
+	rm -f spkmodem-recv