AndroidMkEntries minor refactoring.

This includes a few changes that make AndroidMkEntries more resemble
AndroidMkData, especially in terms of how extra entries are added.
Most importantly it can now have multiple custom functions.

Test: Soong tests
Change-Id: Ibf9102624d16d0c1c9894a2794fc7c797bb34c9a
diff --git a/java/platform_compat_config.go b/java/platform_compat_config.go
index 792edf3..f1da203 100644
--- a/java/platform_compat_config.go
+++ b/java/platform_compat_config.go
@@ -77,9 +77,11 @@
 		Class:      "ETC",
 		OutputFile: android.OptionalPathForPath(p.configFile),
 		Include:    "$(BUILD_PREBUILT)",
-		AddCustomEntries: func(name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
-			entries.SetString("LOCAL_MODULE_PATH", "$(OUT_DIR)/"+p.installDirPath.RelPathString())
-			entries.SetString("LOCAL_INSTALLED_MODULE_STEM", p.configFile.Base())
+		ExtraEntries: []android.AndroidMkExtraEntriesFunc{
+			func(entries *android.AndroidMkEntries) {
+				entries.SetString("LOCAL_MODULE_PATH", "$(OUT_DIR)/"+p.installDirPath.RelPathString())
+				entries.SetString("LOCAL_INSTALLED_MODULE_STEM", p.configFile.Base())
+			},
 		},
 	}
 }