IWYU: add cstdint for uint64_t in sw::LRUCache

Bug: chromium:957519
Change-Id: I70970ceda50dfc38f3d149fea03e8a6a79a35934
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/71268
Commit-Queue: Shahbaz Youssefi <syoussefi@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Shahbaz Youssefi <syoussefi@google.com>
diff --git a/src/System/LRUCache.hpp b/src/System/LRUCache.hpp
index 1c24490..a04cdfa 100644
--- a/src/System/LRUCache.hpp
+++ b/src/System/LRUCache.hpp
@@ -18,6 +18,7 @@
 #include "System/Debug.hpp"
 
 #include <cstddef>
+#include <cstdint>
 #include <functional>
 #include <unordered_set>
 #include <vector>