[PATCH 2/3] sandbox: only test for sdl libs when sdl is enabled

[Sascha Hauer]

Otherwise we get the following warning when sdl is not installed
on the compile host:

Package sdl was not found in the pkg-config search path.
Perhaps you should add the directory containing `sdl.pc'
to the PKG_CONFIG_PATH environment variable
No package 'sdl' found

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 arch/sandbox/Makefile |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/sandbox/Makefile b/arch/sandbox/Makefile
index c0aa8c6..596c8f8 100644
--- a/arch/sandbox/Makefile
+++ b/arch/sandbox/Makefile
@@ -39,10 +39,13 @@ archprepare: maketools
 
 PHONY += maketools
 
-SDL_LIBS-$(CONFIG_DRIVER_VIDEO_SDL) := $(shell pkg-config sdl --libs)
+ifeq ($(CONFIG_DRIVER_VIDEO_SDL),y)
+SDL_LIBS := $(shell pkg-config sdl --libs)
+endif
+
 cmd_barebox__ = $(CC) -o $@ -Wl,-T,$(barebox-lds) \
 	-Wl,--start-group $(barebox-common) -Wl,--end-group \
-	-lrt -lpthread $(SDL_LIBS-y)
+	-lrt -lpthread $(SDL_LIBS)
 
 common-y += $(BOARD) arch/sandbox/os/
 
-- 
1.7.10.4