adb: don't pull symlinks.

Pulling symlinks was broken for directories, and it doesn't seem like
there's a good way to make it not broken, given that the protocol doesn't
have readlink (and we don't want to create symlinks on Windows, anyway).
The behavior for files doesn't seem to be especially useful, either.

Bug: http://b/25601283
Change-Id: Ie1d27e93dd09cbc0c178623b390041d1cb11f726

adb/file_sync_client.cpp

@@ -887,8 +887,7 @@ bool do_sync_pull(const std::vector<const char*>& srcs, const char* dst,
             continue;
         }
 
-        if (S_ISREG(src_mode) || S_ISLNK(src_mode)) {
-            // TODO(b/25601283): symlinks shouldn't be handled as files.
+        if (S_ISREG(src_mode)) {
             std::string path_holder;
             if (dst_isdir) {
                 // If we're copying a remote file to a local directory, we