Add the metalava_enabled property

The new property is added for supporting metalava. But some sdk library
cannot use metalava. So "metalava_enabled: false" is added to these
modules.

Test: make -j
Test: checkapi
Bug: 117127012
Merged-In: Ib65f3cd73dac0ac6ed64afeca6546d99739e4424
Change-Id: Ib65f3cd73dac0ac6ed64afeca6546d99739e4424
(cherry picked from commit 558e702be0)

test-base/Android.bp

@@ -37,7 +37,8 @@ java_sdk_library {
         "junit.framework",
     ],
 
-    droiddoc_options: ["stubsourceonly"],
+    droiddoc_options: ["-stubsourceonly"],
+    metalava_enabled: false,
     compile_dex: true,
 }