Merge pull request #5212 from GregTho/win32close

Use ::_close rather than ::close in Win32 stubs.
diff --git a/src/google/protobuf/stubs/io_win32.cc b/src/google/protobuf/stubs/io_win32.cc
index f00a268..d0f57df 100644
--- a/src/google/protobuf/stubs/io_win32.cc
+++ b/src/google/protobuf/stubs/io_win32.cc
@@ -334,7 +334,7 @@
 #endif
 }
 
-int close(int fd) { return ::close(fd); }
+int close(int fd) { return ::_close(fd); }
 
 int dup(int fd) { return ::_dup(fd); }