Cleaning up CYGWIN define of fread_unlocked to port

Summary: CYGWIN avoided fread_unlocked in a wrong way. Fix it to the standard way.

Test Plan: Run tests

Reviewers: anthony, kradhakrishnan, IslamAbdelRahman, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D42549

port/port_posix.h

@@ -53,7 +53,7 @@
 
 #if defined(OS_MACOSX) || defined(OS_SOLARIS) || defined(OS_FREEBSD) ||\
     defined(OS_NETBSD) || defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD) ||\
-    defined(OS_ANDROID)
+    defined(OS_ANDROID) || defined(OS_CYGWIN)
 // Use fread/fwrite/fflush on platforms without _unlocked variants
 #define fread_unlocked fread
 #define fwrite_unlocked fwrite

util/env_posix.cc

@@ -186,11 +186,7 @@ class PosixSequentialFile: public SequentialFile {
     Status s;
     size_t r = 0;
     do {
-#ifndef CYGWIN
       r = fread_unlocked(scratch, 1, n, file_);
-#else
-      r = fread(scratch, 1, n, file_);
-#endif
     } while (r == 0 && ferror(file_) && errno == EINTR);
     IOSTATS_ADD(bytes_read, r);
     *result = Slice(scratch, r);