bsps: Support .rtemsstack.* linker input sections

Use a dedicated memory region or place it between the BSS and workspace.

Update #3459.

bsps/m32c/m32cbsp/start/linkcmds

@@ -157,6 +157,11 @@ SECTIONS
 
   . += _StackSize;
   PROVIDE (__stack = .);
+
+  .rtemsstack (NOLOAD) : {
+    *(SORT(.rtemsstack.*))
+  } > RAM
+
   PROVIDE (_WorkAreaBase = .);
   . = 0xa00000;
   PROVIDE (_WorkAreaEnd = .);