dex_import that isn't available for platform isn't installed

This change fixes a bug that dex_import module is always installed to
the platform even when the module is not available to the platform.

Exempt-From-Owner-Approval: cherry-pick from AOSP

Bug: 158284983
Test: OUT_DIR=/tmp/ndk build/soong/scripts/build-ndk-prebuilts.sh
Merged-In: I85570506e700be59ee63e4f1d7902a40e36df39c
(cherry picked from commit afd3d11a795b9f331637d3587a94142f20e8c55d)
Change-Id: I85570506e700be59ee63e4f1d7902a40e36df39c
diff --git a/java/java.go b/java/java.go
index 0ba1f5a..ee4b8d8 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2753,8 +2753,10 @@
 
 	j.maybeStrippedDexJarFile = dexOutputFile
 
-	ctx.InstallFile(android.PathForModuleInstall(ctx, "framework"),
-		j.Stem()+".jar", dexOutputFile)
+	if j.IsForPlatform() {
+		ctx.InstallFile(android.PathForModuleInstall(ctx, "framework"),
+			j.Stem()+".jar", dexOutputFile)
+	}
 }
 
 func (j *DexImport) DexJarBuildPath() android.Path {