Moving GSI-specific properties to /system_ext

We're now adding a core CSI system.img that is common across different
targets. So GSI-specific things should be moved to /system_ext.

Also renaming various generic*/system.prop to generic*/system_ext.prop.
This is to put the customization into /system_ext/build.prop instead of
/system/build.prop.

Bug: 137711197
Test: boot a GSI on crosshatch, and checks the value of those properties
Change-Id: Id344124280d5f4a6c10d390a9e8a4a50cc7f28fb
diff --git a/core/Makefile b/core/Makefile
index c9b8cd1..6c90b51 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -597,16 +597,32 @@
 INSTALLED_SYSTEM_EXT_BUILD_PROP_TARGET := $(TARGET_OUT_SYSTEM_EXT)/build.prop
 ALL_DEFAULT_INSTALLED_MODULES += $(INSTALLED_SYSTEM_EXT_BUILD_PROP_TARGET)
 
+ifdef TARGET_SYSTEM_EXT_PROP
+system_ext_prop_files := $(TARGET_SYSTEM_EXT_PROP)
+else
+system_ext_prop_files := $(wildcard $(TARGET_DEVICE_DIR)/system_ext.prop)
+endif
+
 FINAL_SYSTEM_EXT_PROPERTIES += \
     $(call collapse-pairs, $(PRODUCT_SYSTEM_EXT_PROPERTIES))
 FINAL_SYSTEM_EXT_PROPERTIES := $(call uniq-pairs-by-first-component, \
     $(FINAL_SYSTEM_EXT_PROPERTIES),=)
 
-$(INSTALLED_SYSTEM_EXT_BUILD_PROP_TARGET): $(BUILDINFO_COMMON_SH) $(POST_PROCESS_PROPS)
+$(INSTALLED_SYSTEM_EXT_BUILD_PROP_TARGET): $(BUILDINFO_COMMON_SH) $(POST_PROCESS_PROPS) $(system_ext_prop_files)
 	@echo Target system_ext buildinfo: $@
 	@mkdir -p $(dir $@)
 	$(hide) echo > $@
 	$(hide) $(call generate-common-build-props,system_ext,$@)
+	$(hide) $(foreach file,$(system_ext_prop_files), \
+	    if [ -f "$(file)" ]; then \
+	        echo Target system_ext properties from: "$(file)"; \
+	        echo "" >> $@; \
+	        echo "#" >> $@; \
+	        echo "# from $(file)" >> $@; \
+	        echo "#" >> $@; \
+	        cat $(file) >> $@; \
+	        echo "# end of $(file)" >> $@; \
+	    fi;)
 	$(hide) echo "#" >> $@; \
 	        echo "# ADDITIONAL SYSTEM_EXT BUILD PROPERTIES" >> $@; \
 	        echo "#" >> $@;