Fix incorrect reference to IA-64 instead of X86-64.

include/boost/predef/architecture/x86/64.h

@@ -1,5 +1,5 @@
 /*
-Copyright Rene Rivera 2008-2015
+Copyright Rene Rivera 2008-2021
 Distributed under the Boost Software License, Version 1.0.
 (See accompanying file LICENSE_1_0.txt or copy at
 http://www.boost.org/LICENSE_1_0.txt)
@@ -14,7 +14,7 @@ http://www.boost.org/LICENSE_1_0.txt)
 /* tag::reference[]
 = `BOOST_ARCH_X86_64`
 
-http://en.wikipedia.org/wiki/Ia64[Intel IA-64] architecture.
+https://en.wikipedia.org/wiki/X86-64[X86-64] architecture.
 
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