Cast a test-only quartc constant to int64_t so it can be shifted by 32 on android without overflowing.

PiperOrigin-RevId: 245968333
Change-Id: Ifec77ea7e9a203cbfa7a6413e09dffafeb3f73df
diff --git a/quic/quartc/test/random_delay_link.cc b/quic/quartc/test/random_delay_link.cc
index 397a564..edd57e3 100644
--- a/quic/quartc/test/random_delay_link.cc
+++ b/quic/quartc/test/random_delay_link.cc
@@ -17,7 +17,7 @@
 namespace {
 
 // Number of buckets used to define an exponential distribution.
-constexpr int64_t kNumBuckets = 2l << 32;
+constexpr int64_t kNumBuckets = static_cast<int64_t>(2) << 32;
 
 }  // namespace