Use Stem where output file name is expected in APEX

Bug: 157638999
Test: m
Change-Id: I4a4892bc2941cf1301d210fc3107c02f0e7b13b7
diff --git a/apex/androidmk.go b/apex/androidmk.go
index 08d190c..9321ad2 100644
--- a/apex/androidmk.go
+++ b/apex/androidmk.go
@@ -183,7 +183,7 @@
 			// soong_java_prebuilt.mk sets LOCAL_MODULE_SUFFIX := .jar  Therefore
 			// we need to remove the suffix from LOCAL_MODULE_STEM, otherwise
 			// we will have foo.jar.jar
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.builtFile.Base(), ".jar"))
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.Stem(), ".jar"))
 			fmt.Fprintln(w, "LOCAL_SOONG_CLASSES_JAR :=", javaModule.ImplementationAndResourcesJars()[0].String())
 			fmt.Fprintln(w, "LOCAL_SOONG_HEADER_JAR :=", javaModule.HeaderJars()[0].String())
 			fmt.Fprintln(w, "LOCAL_SOONG_DEX_JAR :=", fi.builtFile.String())
@@ -194,13 +194,13 @@
 			// soong_app_prebuilt.mk sets LOCAL_MODULE_SUFFIX := .apk  Therefore
 			// we need to remove the suffix from LOCAL_MODULE_STEM, otherwise
 			// we will have foo.apk.apk
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.builtFile.Base(), ".apk"))
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", strings.TrimSuffix(fi.Stem(), ".apk"))
 			if app, ok := fi.module.(*java.AndroidApp); ok && len(app.JniCoverageOutputs()) > 0 {
 				fmt.Fprintln(w, "LOCAL_PREBUILT_COVERAGE_ARCHIVE :=", strings.Join(app.JniCoverageOutputs().Strings(), " "))
 			}
 			fmt.Fprintln(w, "include $(BUILD_SYSTEM)/soong_app_prebuilt.mk")
 		} else if fi.class == nativeSharedLib || fi.class == nativeExecutable || fi.class == nativeTest {
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.builtFile.Base())
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.Stem())
 			if cc, ok := fi.module.(*cc.Module); ok {
 				if cc.UnstrippedOutputFile() != nil {
 					fmt.Fprintln(w, "LOCAL_SOONG_UNSTRIPPED_BINARY :=", cc.UnstrippedOutputFile().String())
@@ -212,7 +212,7 @@
 			}
 			fmt.Fprintln(w, "include $(BUILD_SYSTEM)/soong_cc_prebuilt.mk")
 		} else {
-			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.builtFile.Base())
+			fmt.Fprintln(w, "LOCAL_MODULE_STEM :=", fi.Stem())
 			if fi.builtFile == a.manifestPbOut && apexType == flattenedApex {
 				if a.primaryApexType {
 					// Make apex_manifest.pb module for this APEX to override all other