urg: make sdl support optional

Only enable SDL support if SDL and SDL_net are already enabled in the
configuration.

[Peter: drop SDL comment]
Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/urg/Config.in

@@ -1,11 +1,8 @@
 config BR2_PACKAGE_URG
 	bool "urg"
 	depends on BR2_INSTALL_LIBSTDCPP
-	select BR2_PACKAGE_SDL
-	select BR2_PACKAGE_SDL_NET
 	help
 	  Library to control Hokuyo's URG series sensors.
-	  Requires SDL & SDL_net.
 
 	  http://www.hokuyo-aut.jp/02sensor/07scanner/download/urg_programs_en/
 

package/urg/urg.mk

@@ -12,10 +12,14 @@ URG_LICENSE_FILES = COPYING
 
 URG_INSTALL_STAGING = YES
 
-URG_DEPENDENCIES = sdl sdl_net
-
-URG_CONF_OPT = --with-sdl-prefix=$(STAGING_DIR)/usr \
+ifeq ($(BR2_PACKAGE_SDL)$(BR2_PACKAGE_SDL_NET),yy)
+URG_DEPENDENCIES += sdl sdl_net
+URG_CONF_OPT += --with-sdl-prefix=$(STAGING_DIR)/usr \
 		--with-sdl-exec-prefix=$(STAGING_DIR)/usr
+else
+URG_CONF_OPT = --without-sdl
+URG_CONF_ENV += ac_cv_path_SDL_CONFIG=""
+endif
 
 URG_CONFIG_SCRIPTS = c_urg-config urg-config