sandbox: Allow puts() output before global_data is set up

We support putc() in this case but not puts(), but this is more useful
since it is what printf() uses.

This particularly affects debugging early in SPL, where currently printf()
statements result in no output. Fix this by adding a special case into
puts() for sandbox, just like putc().

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/common/console.c b/common/console.c
index 9a94f32..0b0dd76 100644
--- a/common/console.c
+++ b/common/console.c
@@ -535,6 +535,13 @@
 
 void puts(const char *s)
 {
+#ifdef CONFIG_SANDBOX
+	/* sandbox can send characters to stdout before it has a console */
+	if (!gd || !(gd->flags & GD_FLG_SERIAL_READY)) {
+		os_puts(s);
+		return;
+	}
+#endif
 #ifdef CONFIG_DEBUG_UART
 	if (!gd || !(gd->flags & GD_FLG_SERIAL_READY)) {
 		while (*s) {