Issue2290: Support x64 Windows builds that live in pcbuild/amd64. Without it,...

Issue2290: Support x64 Windows builds that live in pcbuild/amd64.  Without it, sysutils._python_build() returns the wrong directory, which causes the test_get_config_h_filename method in Lib/distutils/tests/test_sysconfig.py to fail.

sysconfig.py

@@ -23,7 +23,8 @@ PREFIX = os.path.normpath(sys.prefix)
 EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
 
 # Path to the base directory of the project. On Windows the binary may
-# live in project/PCBuild9
+# live in project/PCBuild9.  If we're dealing with an x64 Windows build,
+# it'll live in project/PCbuild/amd64.
 project_base = os.path.dirname(os.path.abspath(sys.executable))
 if os.name == "nt" and "pcbuild" in project_base[-8:].lower():
     project_base = os.path.abspath(os.path.join(project_base, os.path.pardir))
@@ -31,6 +32,10 @@ if os.name == "nt" and "pcbuild" in project_base[-8:].lower():
 if os.name == "nt" and "\\pc\\v" in project_base[-10:].lower():
     project_base = os.path.abspath(os.path.join(project_base, os.path.pardir,
                                                 os.path.pardir))
+# PC/AMD64
+if os.name == "nt" and "\\pcbuild\\amd64" in project_base[-14:].lower():
+    project_base = os.path.abspath(os.path.join(project_base, os.path.pardir,
+                                                os.path.pardir))
 
 # python_build: (Boolean) if true, we're either building Python or
 # building an extension with an un-installed Python, so we use