Stop using _LFS64_LARGEFILE

There is only one place left in the code where strace guesses whether
libc provides LFS64 functions and structures.  The most natural thing to
do there is to check for _LARGEFILE64_SOURCE - the macro provided by
glibc.  Other libc implementations that provide nondegenerate LFS64
interfaces are expected to define this macro as well.

* defs.h (_LFS64_LARGEFILE): Remove.
* strace.c: Use _LARGEFILE64_SOURCE instead of _LFS64_LARGEFILE.

defs.h

@@ -30,12 +30,6 @@
 #ifdef HAVE_CONFIG_H
 # include "config.h"
 #endif
-#ifdef _LARGEFILE64_SOURCE
-/* This is the macro everything checks before using foo64 names.  */
-# ifndef _LFS64_LARGEFILE
-#  define _LFS64_LARGEFILE 1
-# endif
-#endif
 
 #ifdef MIPS
 # include <sgidefs.h>

strace.c

@@ -438,7 +438,7 @@ swap_uid(void)
 	}
 }
 
-#if _LFS64_LARGEFILE
+#ifdef _LARGEFILE64_SOURCE
 # define fopen_for_output fopen64
 # define struct_stat struct stat64
 # define stat_file stat64