Fix TestAarImportProducesJniPackages/aar-no-jni

TestAarImportProducesJniPackages was attempting to assert that an
aar_import module always had a JniPackageProvider, but was instead
asserting that the return type was always a JniPackageInfo.  Since
ModuleProvider returned the zero value of JniPackageInfo even when
there was no provider that was always true.

Fix aar_import to always set JniPackageProvider.

Test: TestAarImportProducesJniPackages
Change-Id: Idaf106e14373490d4eb807892e174aaaf094bbcf

java/aar.go

@@ -1256,12 +1256,12 @@ func (a *AARImport) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 				},
 			})
 		}
+	}
 
 	ctx.SetProvider(JniPackageProvider, JniPackageInfo{
 		JniPackages: a.jniPackages,
 	})
 }
-}
 
 func (a *AARImport) HeaderJars() android.Paths {
 	return android.Paths{a.classpathFile}