Add dependencies for Metalava's implicit android.jar references

Metalava implicitly searches
prebuilts/tools/common/api-versions/android-%/android.jar and
prebuilts/sdk/%/public/android.jar when looking for --android-jar-patterns
matches, and fails if it can't find a match for an API level between 1 and
28 in at least one pattern.  Add android.jar files from the
api_levels_annotations_dirs directories to try to satisfy these patterns.

Bug: 153703940
Test: m docs
Change-Id: I866850b33d9a5cd82cc5135bd8f9e9400ed65439
diff --git a/java/droidstubs.go b/java/droidstubs.go
index b42cb66..be4d8f8 100644
--- a/java/droidstubs.go
+++ b/java/droidstubs.go
@@ -360,7 +360,16 @@
 	ctx.VisitDirectDepsWithTag(metalavaAPILevelsAnnotationsDirTag, func(m android.Module) {
 		if t, ok := m.(*ExportedDroiddocDir); ok {
 			for _, dep := range t.deps {
-				if strings.HasSuffix(dep.String(), filename) {
+				if dep.Base() == filename {
+					cmd.Implicit(dep)
+				}
+				if filename != "android.jar" && dep.Base() == "android.jar" {
+					// Metalava implicitly searches these patterns:
+					//  prebuilts/tools/common/api-versions/android-%/android.jar
+					//  prebuilts/sdk/%/public/android.jar
+					// Add android.jar files from the api_levels_annotations_dirs directories to try
+					// to satisfy these patterns.  If Metalava can't find a match for an API level
+					// between 1 and 28 in at least one pattern it will fail.
 					cmd.Implicit(dep)
 				}
 			}