remove #include port/port.h in public header file

Summary:
break internal build
Closes https://github.com/facebook/rocksdb/pull/2336

Differential Revision: D5097089

Pulled By: lightmark

fbshipit-source-id: 6996cbadeead21074a41e526ea04659190ee61d8

include/rocksdb/iostats_context.h

@@ -7,7 +7,6 @@
 #include <stdint.h>
 #include <string>
 
-#include "port/port.h"
 #include "rocksdb/perf_level.h"
 
 // A thread local context for gathering io-stats efficiently and transparently.
@@ -48,7 +47,12 @@ struct IOStatsContext {
 };
 
 #ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
-extern __thread IOStatsContext iostats_context;
+  #if defined(_MSC_VER) && !defined(__thread)
+    // Thread local storage on Linux
+    // There is thread_local in C++11
+    #define __thread __declspec(thread)
+  #endif
+  extern __thread IOStatsContext iostats_context;
 #endif
 
 }  // namespace rocksdb

include/rocksdb/perf_context.h

@@ -9,7 +9,6 @@
 #include <stdint.h>
 #include <string>
 
-#include "port/port.h"
 #include "rocksdb/perf_level.h"
 
 namespace rocksdb {
@@ -158,6 +157,11 @@ extern PerfContext perf_context;
     PerfContext *getPerfContext();
     #define perf_context (*getPerfContext())
   #else
+    #if defined(_MSC_VER) && !defined(__thread)
+      // Thread local storage on Linux
+      // There is thread_local in C++11
+      #define __thread __declspec(thread)
+    #endif
     extern __thread PerfContext perf_context;
   #endif
 #endif