[bsp] insert keep section .rti_fn* in GCC link file

bsp/frdm-k64f/K64FN1M0xxx12.ld

@@ -88,6 +88,13 @@ SECTIONS
         __vsymtab_end = .;
         . = ALIGN(4);
 
+        /* section information for initial. */
+        . = ALIGN(4);
+        __rt_init_start = .;
+        KEEP(*(SORT(.rti_fn*)))
+        __rt_init_end = .;
+        . = ALIGN(4);
+
         . = ALIGN(4);
         _etext = .;