Added file io test to test0. Added close call to libposix.

tasks/test0/src/fileio.c

@@ -0,0 +1,33 @@
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+#include <tests.h>
+
+int fileio(void)
+{
+	int fd;
+	ssize_t cnt;
+	int err;
+
+	char *str = "I WROTE TO THIS FILE\n";
+
+	if ((fd = open("/home/bahadir/newfile.txt", O_RDWR | O_CREAT | O_TRUNC, S_IRWXU)) < 0) {
+		perror("OPEN");
+		return 0;
+	}
+
+	if ((int)(cnt = write(fd, str, strlen(str))) < 0) {
+		perror("WRITE");
+		return 0;
+	}
+
+	if ((err = close(fd)) < 0)
+		perror("CLOSE");
+
+	return 0;
+}
+