Fix a few warnings/errors for compiling with -fno-exceptions.

llvm-svn: 178267
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: e00e6f23d36a802c7a81876891e4b470513d9cae
diff --git a/src/hash.cpp b/src/hash.cpp
index a013500..75e773a 100644
--- a/src/hash.cpp
+++ b/src/hash.cpp
@@ -155,6 +155,8 @@
 #ifndef _LIBCPP_NO_EXCEPTIONS
     if (N > 0xFFFFFFFB)
         throw overflow_error("__next_prime overflow");
+#else
+    (void)N;
 #endif
 }
 
@@ -166,6 +168,8 @@
 #ifndef _LIBCPP_NO_EXCEPTIONS
     if (N > 0xFFFFFFFFFFFFFFC5ull)
         throw overflow_error("__next_prime overflow");
+#else
+    (void)N;
 #endif
 }