feat: add ffi c

__ffi/c2/Makefile

@@ -0,0 +1,16 @@
+.PHONY: clean
+
+libcfunctions.so: cfunctions.o
+	${CC} --shared -o $@ $<
+
+cfunctions.o: cfunctions.h cfunctions.c
+	${CC} -fPIC -o $@ -c cfunctions.c -I.
+
+something: something.rs libcfunctions.so
+	rustc -L. -lcfunctions something.rs -C link-arg='-Wl,-rpath,${PWD}'
+	@# The command below can be used if the library to link with is
+	@# specified in something.rs.
+	@#rustc -L. something.rs -C link-arg='-Wl,-rpath,${PWD}'
+clean: 
+	${RM} libcfunctions.so cfunctions.o something
+