Revert "sandbox: remove os_putc() and os_puts()"

While sandbox works OK without the special-case code, it does result in
console output being stored in the pre-console buffer while sandbox starts
up. If there is a crash or a problem then there is no indication of what
is going on.

For ease of debugging it seems better to revert this change.

This reverts commit 47b98ad0f6779485d0f0c14f337c3eece273eb54.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index c524957..9dd90a1 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -421,6 +421,17 @@
 	return 0;
 }
 
+void os_putc(int ch)
+{
+	putchar(ch);
+}
+
+void os_puts(const char *str)
+{
+	while (*str)
+		os_putc(*str++);
+}
+
 int os_write_ram_buf(const char *fname)
 {
 	struct sandbox_state *state = state_get_current();