Rename DexJar interface method to DexJarBuildPath.

This is a prerequisite change before adding DexJarInstallPath.

Test: lunch aosp_cf_phone-userdebug && m
Change-Id: I033e08b8bb06c0a844a6bbbfcdc48ce33e9c95cf
diff --git a/apex/apex.go b/apex/apex.go
index d3c5df0..7a66b2e 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -1656,7 +1656,7 @@
 
 func apexFileForJavaLibrary(ctx android.BaseModuleContext, lib javaDependency, module android.Module) apexFile {
 	dirInApex := "javalib"
-	fileToCopy := lib.DexJar()
+	fileToCopy := lib.DexJarBuildPath()
 	af := newApexFile(ctx, fileToCopy, module.Name(), dirInApex, javaSharedLib, module)
 	af.jacocoReportClassesFile = lib.JacocoReportClassesFile()
 	af.stem = lib.Stem() + ".jar"