check first XSPN result value in FW, add gcc_except_table, replace

self-made printf with one from the lib.

raven_spn/bsp/env/freedom-e300-hifive1/flash.lds

@@ -104,6 +104,11 @@ SECTIONS
     KEEP (*(.dtors))
   } >flash AT>flash :flash
 
+  .except :
+  {
+  	*(.gcc_except_table.*)
+  } >flash AT>flash :flash
+  
   .lalign         :
   {
     . = ALIGN(4);