Enable building cross components from linux-arm64 (#99252)

* Enable building cross components from linux-arm64

* Update error message

Author: am11

eng/native/configureplatform.cmake

@@ -27,6 +27,8 @@ if(CLR_CMAKE_HOST_OS STREQUAL linux)
             endif()
         elseif(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL i686)
             set(CLR_CMAKE_HOST_UNIX_X86 1)
+        elseif(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL aarch64)
+            set(CLR_CMAKE_HOST_UNIX_ARM64 1)
         else()
             clr_unknown_arch()
         endif()

eng/native/functions.cmake

@@ -1,8 +1,8 @@
 function(clr_unknown_arch)
     if (WIN32)
-        message(FATAL_ERROR "Only AMD64, ARM64, ARM and I386 are supported. Found: ${CMAKE_SYSTEM_PROCESSOR}")
+        message(FATAL_ERROR "Only AMD64, ARM64, ARM and I386 hosts are supported. Found: ${CMAKE_SYSTEM_PROCESSOR}")
     elseif(CLR_CROSS_COMPONENTS_BUILD)
-        message(FATAL_ERROR "Only AMD64, I386 host are supported for linux cross-architecture component. Found: ${CMAKE_SYSTEM_PROCESSOR}")
+        message(FATAL_ERROR "Only AMD64, ARM64 and I386 hosts are supported for linux cross-architecture component. Found: ${CMAKE_SYSTEM_PROCESSOR}")
     else()
         message(FATAL_ERROR "'${CMAKE_SYSTEM_PROCESSOR}' is an unsupported architecture.")
     endif()