lineage: 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

build/soong/soong_config.mk

@@ -9,7 +9,7 @@ $(call add_json_str, Java_Source_Overlays, $(JAVA_SOURCE_OVERLAYS))
 $(call add_json_bool, Needs_text_relocations, $(filter true,$(TARGET_NEEDS_PLATFORM_TEXT_RELOCATIONS)))
 $(call add_json_str, Specific_camera_parameter_library, $(TARGET_SPECIFIC_CAMERA_PARAMETER_LIBRARY))
 $(call add_json_str_omitempty, Target_process_sdk_version_override, $(TARGET_PROCESS_SDK_VERSION_OVERRIDE))
-$(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),,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)))