test: Record and silence console in tests

When running sandbox tests, silence the console to avoid unwanted output.
Also, record the console in case tests want to check it.

The -v option can be used to enable stdout during tests.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/include/asm/state.h b/arch/sandbox/include/asm/state.h
index e876ba2..11856c2 100644
--- a/arch/sandbox/include/asm/state.h
+++ b/arch/sandbox/include/asm/state.h
@@ -64,6 +64,7 @@
 	bool reset_allowed[RESET_COUNT];	/* Allowed reset types */
 	enum state_terminal_raw term_raw;	/* Terminal raw/cooked */
 	bool skip_delays;		/* Ignore any time delays (for test) */
+	bool show_test_output;		/* Don't suppress stdout in tests */
 
 	/* Pointer to information for each SPI bus/cs */
 	struct sandbox_spi_info spi[CONFIG_SANDBOX_SPI_MAX_BUS]