ARMClang: Separate cpu/arch flags from preceding flags

Suggested-by: Kim Kryger

Modules/Compiler/ARMClang.cmake

@@ -89,12 +89,12 @@ macro(__compiler_armclang lang)
   else()
     __armclang_check_processor("${CMAKE_SYSTEM_ARCH}" "${CMAKE_${lang}_COMPILER_ARCH_LIST}" _CMAKE_${lang}_CHECK_ARCH_RESULT)
     if( _CMAKE_${lang}_CHECK_ARCH_RESULT)
-      string(APPEND CMAKE_${lang}_FLAGS_INIT "-march=${CMAKE_SYSTEM_ARCH}")
+      string(APPEND CMAKE_${lang}_FLAGS_INIT " -march=${CMAKE_SYSTEM_ARCH}")
       set(__march_flag_set TRUE)
     endif()
     __armclang_check_processor("${CMAKE_SYSTEM_PROCESSOR}" "${CMAKE_${lang}_COMPILER_PROCESSOR_LIST}" _CMAKE_${lang}_CHECK_PROCESSOR_RESULT)
     if(_CMAKE_${lang}_CHECK_PROCESSOR_RESULT)
-      string(APPEND CMAKE_${lang}_FLAGS_INIT "-mcpu=${CMAKE_SYSTEM_PROCESSOR}")
+      string(APPEND CMAKE_${lang}_FLAGS_INIT " -mcpu=${CMAKE_SYSTEM_PROCESSOR}")
       set(__mcpu_flag_set TRUE)
     endif()
     if(NOT __march_flag_set AND NOT __mcpu_flag_set)
@@ -111,7 +111,7 @@ macro(__compiler_armclang lang)
   list(TRANSFORM CMAKE_LINKER_CPU_LIST TOLOWER)
   __armclang_check_processor("${CMAKE_SYSTEM_PROCESSOR}" "${CMAKE_LINKER_CPU_LIST}" _CMAKE_CHECK_LINK_CPU_RESULT)
   if(_CMAKE_CHECK_LINK_CPU_RESULT)
-    string(APPEND CMAKE_${lang}_LINK_FLAGS "--cpu=${CMAKE_SYSTEM_PROCESSOR}")
+    string(APPEND CMAKE_${lang}_LINK_FLAGS " --cpu=${CMAKE_SYSTEM_PROCESSOR}")
   endif()
 
   if(__CMAKE_ARMClang_USING_armlink)