Quash a whole bunch of warnings

llvm-svn: 145624
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: c206366fd7774aff222578c2680b931a4c2c35ba
diff --git a/src/hash.cpp b/src/hash.cpp
index 728b9bd..6f30d5a 100644
--- a/src/hash.cpp
+++ b/src/hash.cpp
@@ -181,7 +181,8 @@
     // Select first potential prime >= n
     //   Known a-priori n >= L
     size_t k0 = n / L;
-    size_t in = std::lower_bound(indices, indices + M, n - k0 * L) - indices;
+    size_t in = static_cast<size_t>(std::lower_bound(indices, indices + M, n - k0 * L)
+                                    - indices);
     n = L * k0 + indices[in];
     while (true)
     {