First Commit - API Tested and functional

.env/Lib/site-packages/greenlet/platform/switch_arm64_msvc.h

@@ -0,0 +1,17 @@
+/*
+ * this is the internal transfer function.
+ *
+ * HISTORY
+ * 21-Oct-21  Niyas Sait  <niyas.sait@linaro.org>
+ *      First version to enable win/arm64 support.
+ */
+
+#define STACK_REFPLUS 1
+#define STACK_MAGIC 0
+
+/* Use the generic support for an external assembly language slp_switch function. */
+#define EXTERNAL_ASM
+
+#ifdef SLP_EVAL
+/* This always uses the external masm assembly file. */
+#endif