Merge META-INF/services/* files in merge_zips -jar

kotlinx_coroutines_test and kotlinx_coroutine_android each provide a
META-INF/services/kotlinx.coroutines.CoroutineExceptionHandler with
different contents, and the final contents needs to be the combination
of the two files.  Implement service merging in merge_zips when the
-jar argument is provided.

Bug: 290933559
Test: TestMergeZips
Change-Id: I69f80d1265c64c671d308ef4cdccfa1564abe056

third_party/zip/android.go

@@ -170,7 +170,7 @@ func (w *Writer) CreateCompressedHeader(fh *FileHeader) (io.WriteCloser, error)
 func (w *Writer) CreateHeaderAndroid(fh *FileHeader) (io.Writer, error) {
 	writeDataDescriptor := fh.Method != Store
 	if writeDataDescriptor {
-		fh.Flags &= DataDescriptorFlag
+		fh.Flags |= DataDescriptorFlag
 	} else {
 		fh.Flags &= ^uint16(DataDescriptorFlag)
 	}