Add support for JNI libraries to android_app modules

Make android_app modules a MultiTargets module, which means the
common variant will have a list of Targets that it needs to handle.
Collect JNI libraries for each Target, and package them into or
alongside the APK.

Bug: 80095087
Test: app_test.go
Change-Id: Iabd3921e1d4c4b4cfcc7e131a0b0d9ab83b0ebbb

java/androidmk.go

@@ -243,6 +243,10 @@ func (app *AndroidApp) AndroidMk() android.AndroidMkData {
 				if len(app.appProperties.Overrides) > 0 {
 					fmt.Fprintln(w, "LOCAL_OVERRIDES_PACKAGES := "+strings.Join(app.appProperties.Overrides, " "))
 				}
+
+				for _, jniLib := range app.installJniLibs {
+					fmt.Fprintln(w, "LOCAL_SOONG_JNI_LIBS_"+jniLib.target.Arch.ArchType.String(), "+=", jniLib.name)
+				}
 			},
 		},
 	}