Fix Windows build

Summary:
Fix 2 issues that was breaking Windows build
1) double to size_t potential downcast warning
2) port_posix is not ready for windows, avoiding building hash_table_bench to
avoid build break

Test Plan: compile in Windoes and make check

Reviewers: sdong, andrewkr

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D59265

Author: krad

utilities/persistent_cache/hash_table_bench.cc

@@ -4,7 +4,7 @@
 //  of patent rights can be found in the PATENTS file in the same directory.
 //
 
-#ifndef ROCKSDB_LITE
+#if !defined(OS_WIN) && !defined(ROCKSDB_LITE)
 
 #ifndef GFLAGS
 #include <cstdio>
@@ -18,8 +18,8 @@ int main() { fprintf(stderr, "Please install gflags to run tools\n"); }
 #include <string>
 #include <unordered_map>
 
-#include "include/rocksdb/env.h"
 #include "port/port_posix.h"
+#include "rocksdb/env.h"
 #include "util/mutexlock.h"
 #include "utilities/persistent_cache/hash_table.h"
 

utilities/persistent_cache/persistent_cache_tier.h

@@ -192,7 +192,8 @@ struct PersistentCacheOptions {
   // file size in order to avoid dead lock.
   size_t write_buffer_count() const {
     assert(write_buffer_size);
-    return (writer_qdepth + 1.2) * cache_file_size / write_buffer_size;
+    return static_cast<size_t>((writer_qdepth + 1.2) * cache_file_size /
+                               write_buffer_size);
   }
 
   // writer-dispatch-size