Set prebuiltCommon.installedFile for apex_set modules

apex_set modules failed to set prebuiltCommon.installedFile, which
caused LOCAL_SOONG_INSTALLED_MODULE to be empty and base_rules.mk
to create a duplicate install rule.  Set it to the path to the
apex file installed by Soong.

Bug: 204136549
Bug: 209867137
Test: m SOONG_CONFIG_art_module_source_build=false
Change-Id: Ia7fec09598823343242ebd44f1732e6bba21d027
diff --git a/apex/prebuilt.go b/apex/prebuilt.go
index 84bdcdd..254c90e 100644
--- a/apex/prebuilt.go
+++ b/apex/prebuilt.go
@@ -965,7 +965,7 @@
 
 	a.installDir = android.PathForModuleInstall(ctx, "apex")
 	if a.installable() {
-		ctx.InstallFile(a.installDir, a.installFilename, a.outputApex)
+		a.installedFile = ctx.InstallFile(a.installDir, a.installFilename, a.outputApex)
 	}
 
 	// in case that apex_set replaces source apex (using prefer: prop)