sandbox: Provide a build option to avoid using SDL

Some machines do not have SDL libraries installed, and it is still useful
to build sandbox without LCD/keyboard support.

Add an option for this, used as follows:

    make sandbox_config all NO_SDL=1

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/config.mk

@@ -18,3 +18,9 @@ cmd_u-boot__ = $(CC) -o $@ -T u-boot.lds \
 	$(PLATFORM_LIBS) -Wl,-Map -Wl,u-boot.map
 
 CONFIG_ARCH_DEVICE_TREE := sandbox
+
+# Define this to avoid linking with SDL, which requires SDL libraries
+# This can solve 'sdl-config: Command not found' errors
+ifneq ($(NO_SDL),)
+PLATFORM_CPPFLAGS += -DSANDBOX_NO_SDL
+endif

include/configs/sandbox.h

@@ -140,8 +140,6 @@
 #define CONFIG_CROS_EC
 #define CONFIG_CMD_CROS_EC
 #define CONFIG_CROS_EC_SANDBOX
-#define CONFIG_KEYBOARD
-#define CONFIG_CROS_EC_KEYB
 #define CONFIG_ARCH_EARLY_INIT_R
 #define CONFIG_BOARD_LATE_INIT
 
@@ -149,7 +147,12 @@
 #define CONFIG_SOUND_SANDBOX
 #define CONFIG_CMD_SOUND
 
+#ifndef SANDBOX_NO_SDL
 #define CONFIG_SANDBOX_SDL
+#endif
+
+/* LCD and keyboard require SDL support */
+#ifdef CONFIG_SANDBOX_SDL
 #define CONFIG_LCD
 #define CONFIG_VIDEO_SANDBOX_SDL
 #define CONFIG_CMD_BMP
@@ -158,9 +161,18 @@
 #define CONFIG_SYS_CONSOLE_IS_IN_ENV
 #define LCD_BPP			LCD_COLOR16
 
+#define CONFIG_CROS_EC_KEYB
+#define CONFIG_KEYBOARD
+
 #define CONFIG_EXTRA_ENV_SETTINGS	"stdin=serial,cros-ec-keyb\0" \
 					"stdout=serial,lcd\0" \
 					"stderr=serial,lcd\0"
+#else
+
+#define CONFIG_EXTRA_ENV_SETTINGS	"stdin=serial\0" \
+					"stdout=serial,lcd\0" \
+					"stderr=serial,lcd\0"
+#endif
 
 #define CONFIG_GZIP_COMPRESSED
 #define CONFIG_BZIP2