file_sync_client.cpp: include strerror() in adb_read() failures.

Bug: http://b/361812738
Change-Id: I40ef6c47731e1f1adb9dd5e8c5a90cb5b7e5ebc1

client/file_sync_client.cpp

@@ -836,7 +836,7 @@ class SyncConnection {
                     const ssize_t bytes_left = amount - buf.size();
                     ssize_t rc = adb_read(fd, buf.end(), bytes_left);
                     if (rc <= 0) {
-                        Error("failed to read copy response");
+                        Error("failed to read copy response: %s", rc < 0 ? strerror(errno) : "EOF");
                         return ReadStatus::Failure;
                     }
                     buf.resize(buf.size() + rc);