Build libc, libm and libcrt with vortex mode

RV_preload.cmake

@@ -57,8 +57,8 @@ foreach (xlen ${RV_XLEN})
 
 
         foreach(lang C;CXX;ASM)
-            set(BUILTINS_${target}_CMAKE_${lang}_FLAGS "--target=${target} -march=${march}" CACHE STRING "") #mabi auto
-            set(RUNTIMES_${target}_CMAKE_${lang}_FLAGS "--target=${target} -march=${march}" CACHE STRING "")
+            set(BUILTINS_${target}_CMAKE_${lang}_FLAGS "-Xclang -target-feature -Xclang +vortex --target=${target} -march=${march}" CACHE STRING "") #mabi auto
+            set(RUNTIMES_${target}_CMAKE_${lang}_FLAGS "-Xclang -target-feature -Xclang +vortex --target=${target} -march=${march}" CACHE STRING "")
         endforeach()
 
         set(RUNTIMES_${target}_CMAKE_SYSTEM_NAME                Generic CACHE STRING "")