Avoid exposing STARPU_BUILD_DIR in installed binaries

---
 examples/ppm_downscaler/yuv_downscaler.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/examples/ppm_downscaler/yuv_downscaler.c
+++ b/examples/ppm_downscaler/yuv_downscaler.c
@@ -48,8 +48,8 @@ void parse_args(int argc, char **argv)
 	}
 	else
 	{
-		snprintf(filename_in, 1024, "%s/examples/ppm_downscaler/%s", STARPU_BUILD_DIR, filename_in_default);
-		snprintf(filename_out, 1024, "%s/examples/ppm_downscaler/%s", STARPU_BUILD_DIR, filename_out_default);
+		fprintf(stderr,"missing input\n");
+		exit(EXIT_FAILURE);
 	}
 }
 
