Fix detecting arhitecture on raspberry pi

Detect arhotecture depending on size of void

Related to #1329

tools/cmake/helpers/platform.cmake

@@ -74,20 +74,16 @@ function(get_os OS)
 endfunction()
 
 function(get_arch ARCH)
-  if(ARCH_X86)
+  if( CMAKE_SIZEOF_VOID_P MATCHES 8 )
+    # void ptr = 8 byte --> x86_64
+    set(${ARCH} "x86_64" PARENT_SCOPE) 
+  elseif( CMAKE_SIZEOF_VOID_P MATCHES 4 )
+    # void ptr = 4 byte --> x86
     set(${ARCH} "x86" PARENT_SCOPE)
-  elseif(ARCH_X64)
-    set(${ARCH} "x64" PARENT_SCOPE)
   else()
-    if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "i386")
-      set(${ARCH} "x86" PARENT_SCOPE)
-    elseif(${CMAKE_SYSTEM_PROCESSOR} MATCHES "x86_64")
-      set(${ARCH} "x64" PARENT_SCOPE)
-    else()
       message(FATAL_ERROR "Unsupported architecture")
-    endif()
-  endif()
-endfunction()
+  endif()    
+endfunction(get_arch ARCH)
 
 function(get_sdk SDK)
   if(SDK_QT)