use __amd64__ instead, until lint is fixed

src/lib/libc/stdlib/strtod.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: strtod.c,v 1.25 2006/10/12 00:27:47 deraadt Exp $ */
+/*	$OpenBSD: strtod.c,v 1.26 2006/10/12 01:49:34 deraadt Exp $ */
 /****************************************************************
  *
  * The author of this software is David M. Gay.
@@ -92,7 +92,7 @@
 #if defined(__m68k__) || defined(__sparc__) || defined(__i386__) || \
     defined(__mips__) || defined(__ns32k__) || defined(__alpha__) || \
     defined(__powerpc__) || defined(__m88k__) || defined(__hppa__) || \
-    defined(__x86_64__) || defined(__sh__) || \
+    defined(__amd64__) || defined(__sh__) || \
     (defined(__arm__) && defined(__VFP_FP__))
 
 #include <sys/types.h>