Remove "#ifdef WIN32" guards from src/port/win32*.c

These files are only compiled on Windows, and most of them didn't have
"#ifdef WIN32" guards. Remove them from the few that did, for
consistency.

Author: Tristan Partin
Discussion: https://www.postgresql.org/message-id/CXGM9RYSXA2J.1DBO4MRXGZA9P@neon.tech

src/port/win32common.c

@@ -19,8 +19,6 @@
 #include "postgres.h"
 #endif
 
-#ifdef WIN32
-
 /*
  * pgwin32_get_file_type
  *
@@ -64,5 +62,3 @@ pgwin32_get_file_type(HANDLE hFile)
 
 	return fileType;
 }
-
-#endif							/* WIN32 */

src/port/win32fseek.c

@@ -17,7 +17,7 @@
 #include "postgres.h"
 #endif
 
-#if defined(WIN32) && defined(_MSC_VER)
+#ifdef _MSC_VER
 
 /*
  * _pgfseeko64
@@ -72,4 +72,4 @@ _pgftello64(FILE *stream)
 	return -1;
 }
 
-#endif							/* defined(WIN32) && defined(_MSC_VER) */
+#endif							/* _MSC_VER */

src/port/win32stat.c

@@ -13,8 +13,6 @@
  *-------------------------------------------------------------------------
  */
 
-#ifdef WIN32
-
 #include "c.h"
 #include "port/win32ntdll.h"
 
@@ -302,5 +300,3 @@ _pgfstat64(int fileno, struct stat *buf)
 	buf->st_nlink = 1;
 	return 0;
 }
-
-#endif							/* WIN32 */