[cmake] Only build for targets newer than TARGET

Build only for targets newer than TARGET when DYNAMIC_ARCH is enabled and a TARGET is selected.
I don't know how to implement this for Makefiles

cmake/arch.cmake

@@ -82,6 +82,10 @@ if (DYNAMIC_ARCH)
       set(DYNAMIC_CORE ${DYNAMIC_CORE} SKYLAKEX COOPERLAKE)
       string(REGEX REPLACE "-march=native" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
     endif ()
+    if(TARGET)
+      list(FIND DYNAMIC_CORE ${TARGET} TARGET_INDEX)
+      list(SUBLIST DYNAMIC_CORE ${TARGET_INDEX} -1 DYNAMIC_CORE)
+    endif()
     if (DYNAMIC_LIST)
       set(DYNAMIC_CORE PRESCOTT ${DYNAMIC_LIST})
     endif ()