Remove HEADER_BSS_FILE_C module include guard

This include guard inside an object file comes as a surprise and
serves no purpose anymore. It seems like this object file was
included by crypto/threads/mttest.c at some time, but the include
directive was removed in commit bb8abd67.
Reviewed-by: NRichard Levitte <levitte@openssl.org>
Reviewed-by: NBernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/9365)

crypto/bio/bss_file.c

@@ -7,10 +7,7 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_BSS_FILE_C
-# define HEADER_BSS_FILE_C
-
-# if defined(__linux) || defined(__sun) || defined(__hpux)
+#if defined(__linux) || defined(__sun) || defined(__hpux)
 /*
  * Following definition aliases fopen to fopen64 on above mentioned
  * platforms. This makes it possible to open and sequentially access files
@@ -26,14 +23,14 @@
 # ifndef _FILE_OFFSET_BITS
 #  define _FILE_OFFSET_BITS 64
 # endif
-# endif
+#endif
 
-# include <stdio.h>
-# include <errno.h>
-# include "bio_lcl.h"
-# include <openssl/err.h>
+#include <stdio.h>
+#include <errno.h>
+#include "bio_lcl.h"
+#include <openssl/err.h>
 
-# if !defined(OPENSSL_NO_STDIO)
+#if !defined(OPENSSL_NO_STDIO)
 
 static int file_write(BIO *h, const char *buf, int num);
 static int file_read(BIO *h, char *buf, int size);
@@ -72,9 +69,9 @@ BIO *BIO_new_file(const char *filename, const char *mode)
         SYSerr(SYS_F_FOPEN, get_last_sys_error());
         ERR_add_error_data(5, "fopen('", filename, "','", mode, "')");
         if (errno == ENOENT
-# ifdef ENXIO
+#ifdef ENXIO
             || errno == ENXIO
-# endif
+#endif
             )
             BIOerr(BIO_F_BIO_NEW_FILE, BIO_R_NO_SUCH_FILE);
         else
@@ -422,6 +419,4 @@ BIO *BIO_new_file(const char *filename, const char *mode)
     return NULL;
 }
 
-# endif                         /* OPENSSL_NO_STDIO */
-
-#endif                          /* HEADER_BSS_FILE_C */
+#endif                         /* OPENSSL_NO_STDIO */