vp9_spatial_svc_encoder.sh: Prevent failures when ssvc is unavailable.

Avoid running the tests when CONFIG_SPATIAL_SVC is 0.

Change-Id: I9b87ed206a9ba7de6827594fba275bd3f60faf2d

test/vp9_spatial_svc_encoder.sh

diff --git a/test/vp9_spatial_svc_encoder.sh b/test/vp9_spatial_svc_encoder.sh
index a5728f6..b48b9e1 100755
--- a/test/vp9_spatial_svc_encoder.sh
+++ b/test/vp9_spatial_svc_encoder.sh
@@ -88,4 +88,8 @@
                        vp9_spatial_svc_mode_ip
                        vp9_spatial_svc_mode_gf"
 
-run_tests vp9_spatial_svc_encoder_verify_environment "${vp9_spatial_svc_tests}"
+if [ "$(vpx_config_option_enabled CONFIG_SPATIAL_SVC)" = "yes" ]; then
+  run_tests \
+    vp9_spatial_svc_encoder_verify_environment \
+    "${vp9_spatial_svc_tests}"
+fi