add libc building to agbcc.

libc/syscalls/syswrite.c

@@ -0,0 +1,17 @@
+/* connector for write */
+
+#include <reent.h>
+#include <unistd.h>
+
+int
+write (fd, buf, cnt)
+     int fd;
+     const void *buf;
+     size_t cnt;
+{
+#ifdef REENTRANT_SYSCALLS_PROVIDED
+  return _write_r (_REENT, fd, buf, cnt);
+#else
+  return _write (fd, buf, cnt);
+#endif
+}