Use ARM64 tools when building on ARM64 hosts (#104695)

* Use ARM64 tools when building on ARM64 hosts

* Fix cross-compiling arm64 from x64

* Update src/coreclr/build-runtime.cmd

Co-authored-by: Steve <hez2010@outlook.com>

---------

Co-authored-by: Steve <hez2010@outlook.com>

Author: eiriktsarpalis

eng/native/init-vs-env.cmd

@@ -6,9 +6,8 @@
 set "__VCBuildArch="
 if /i "%~1" == "x86"   (set __VCBuildArch=x86)
 if /i "%~1" == "x64"   (set __VCBuildArch=x86_amd64)
-if /i "%~1" == "arm"   (set __VCBuildArch=x86_arm)
-if /i "%~1" == "arm64" (set __VCBuildArch=x86_arm64)
-if /i "%~1" == "wasm" (if /i "%PROCESSOR_ARCHITECTURE%" == "ARM64" (set __VCBuildArch=x86_arm64) else (set __VCBuildArch=x86_amd64))
+if /i "%~1" == "arm64" (if /i "%PROCESSOR_ARCHITECTURE%" == "ARM64" (set __VCBuildArch=arm64) else (set __VCBuildArch=x86_arm64))
+if /i "%~1" == "wasm" (if /i "%PROCESSOR_ARCHITECTURE%" == "ARM64" (set __VCBuildArch=arm64) else (set __VCBuildArch=x86_amd64))
 
 :: Default to highest Visual Studio version available that has Visual C++ tools.
 ::

src/coreclr/build-runtime.cmd

@@ -363,11 +363,8 @@ if %__BuildNative% EQU 1 (
     REM Set the environment for the native build
     set __VCTargetArch=amd64
     if /i "%__HostArch%" == "x86" ( set __VCTargetArch=x86 )
-    if /i "%__HostArch%" == "arm" (
-        set __VCTargetArch=x86_arm
-    )
     if /i "%__HostArch%" == "arm64" (
-        set __VCTargetArch=x86_arm64
+        if /i "%__ProcessorArch%" == "ARM64" (set __VCTargetArch=arm64) else (set __VCTargetArch=x86_arm64)
     )
 
     if NOT DEFINED SkipVCEnvInit (