Windows: target arch based on spec target arch (#35797)

Update packages to check Spec's target rather than the host platform.

var/spack/repos/builtin/packages/7zip/package.py

@@ -70,7 +70,7 @@ def plat_arch(self):
         return arch
 
     def is_64bit(self):
-        return platform.machine().endswith("64")
+        return "64" in self.pkg.spec.target.family
 
     def build(self, spec, prefix):
         link_type = "1" if "static" in spec.variants["link_type"].value else "0"

var/spack/repos/builtin/packages/msmpi/package.py

@@ -4,7 +4,6 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import os
-import platform
 import re
 import sys
 
@@ -58,7 +57,7 @@ def setup_build_environment(self, env):
         env.set("SPACK_IFORT", ifort_root)
 
     def is_64bit(self):
-        return platform.machine().endswith("64")
+        return "64" in self.pkg.spec.target.family
 
     def build_command_line(self):
         args = ["-noLogo"]

var/spack/repos/builtin/packages/perl/package.py

@@ -12,7 +12,6 @@
 # Date: September 6, 2015
 #
 import os
-import platform
 import re
 import sys
 from contextlib import contextmanager
@@ -227,7 +226,7 @@ def nmake_arguments(self):
         return args
 
     def is_64bit(self):
-        return platform.machine().endswith("64")
+        return "64" in self.pkg.spec.target.family
 
     def configure_args(self):
         spec = self.spec