bliss: Use add_json_str_omitempty directive for TARGET_LD_SHIM_LIBS

* The code is ifdef'ed out, so let's match that expecation here

Change-Id: I59c8e276c3dd28c4f46222f66d626e48b2aa6551
Signed-off-by: Jackeagle <jackeagle102@gmail.com>
diff --git a/build/soong/soong_config.mk b/build/soong/soong_config.mk
index 40266f2..d4ea787 100644
--- a/build/soong/soong_config.mk
+++ b/build/soong/soong_config.mk
@@ -6,7 +6,7 @@
 $(call add_json_str_omitempty, Additional_gralloc_10_usage_bits, $(TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS))
 $(call add_json_bool, Has_legacy_camera_hal1,                $(filter true,$(TARGET_HAS_LEGACY_CAMERA_HAL1)))
 $(call add_json_str,  Specific_camera_parameter_library,     $(TARGET_SPECIFIC_CAMERA_PARAMETER_LIBRARY))
-$(call add_json_str,  Target_shim_libs,                      $(TARGET_LD_SHIM_LIBS))
+$(call add_json_str_omitempty, Target_shim_libs,             $(TARGET_LD_SHIM_LIBS))
 $(call add_json_bool, Uses_generic_camera_parameter_library, $(if $(TARGET_SPECIFIC_CAMERA_PARAMETER_LIBRARY),false,true))
 $(call add_json_bool, Uses_nvidia_enhancements,              $(filter TRUE,$(NV_ANDROID_FRAMEWORK_ENHANCEMENTS)))
 $(call add_json_bool, Uses_qcom_bsp_legacy,                  $(filter true,$(TARGET_USES_QCOM_BSP_LEGACY)))