bind: keep package function comments in java file

previously package level function comments are ignored. this change
keeps the comment in generated java files

Change-Id: I86dcd93b1026c4455d2c4782cbc9f30b514b3107
Reviewed-on: https://go-review.googlesource.com/c/mobile/+/181038
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/bind/genjava.go b/bind/genjava.go
index d4d6eb0..e5d31de 100644
--- a/bind/genjava.go
+++ b/bind/genjava.go
@@ -1655,6 +1655,7 @@
 			g.Printf("// skipped function %s with unsupported parameter or return types\n\n", f.Name())
 			continue
 		}
+		g.javadoc(g.docs[f.Name()].Doc())
 		g.Printf("public static native ")
 		g.genFuncSignature(f, nil, false)
 	}
diff --git a/bind/testdata/doc.java.golden b/bind/testdata/doc.java.golden
index 8a2ac77..90172e7 100644
--- a/bind/testdata/doc.java.golden
+++ b/bind/testdata/doc.java.golden
@@ -308,6 +308,12 @@
      */
     public static native String getV();
     
+    /**
+     * F is a function.
+     */
     public static native void f();
+    /**
+     * NewS is a constructor.
+     */
     public static native S newS();
 }