build: accept ARM64 as aarch64

Windows spells AArch64 as ARM64.  Take the opportunity to collapse the
AMD64 case as well.

Author: compnerd

CMakeLists.txt

@@ -621,9 +621,9 @@ endif()
 if(SWIFT_HOST_VARIANT_ARCH)
   set(SWIFT_HOST_VARIANT_ARCH_default "${SWIFT_HOST_VARIANT_ARCH}")
 else()
-  if("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64")
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64")
     set(SWIFT_HOST_VARIANT_ARCH_default "x86_64")
-  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "aarch64")
+  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|ARM64")
     set(SWIFT_HOST_VARIANT_ARCH_default "aarch64")
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "ppc64")
     set(SWIFT_HOST_VARIANT_ARCH_default "powerpc64")
@@ -636,8 +636,6 @@ else()
     set(SWIFT_HOST_VARIANT_ARCH_default "armv6")
   elseif("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "armv7l|armv7-a")
     set(SWIFT_HOST_VARIANT_ARCH_default "armv7")
-  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "AMD64")
-    set(SWIFT_HOST_VARIANT_ARCH_default "x86_64")
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "IA64")
     set(SWIFT_HOST_VARIANT_ARCH_default "itanium")
   elseif("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(x86|i686)")