bsps: Support .rtemsstack.* linker input sections

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

Update #3459.

bsps/sh/gensh4/start/linkcmds

@@ -144,11 +144,14 @@ SECTIONS
    __bss_end = .;
   } > ram
 
-  .stack . : {
+  .stack : {
     . = . + 4096;
-  }
+  } > ram
+
+  .rtemsstack (NOLOAD) : {
+    *(SORT(.rtemsstack.*))
+  } > ram
 
-  . = ALIGN(16);
   _WorkAreaBase = . ;
 
   . = ALIGN(16);
@@ -188,6 +191,5 @@ SECTIONS
   .debug_funcnames 0 : { *(.debug_funcnames) }
   .debug_typenames 0 : { *(.debug_typenames) }
   .debug_varnames  0 : { *(.debug_varnames) }
-  .stack : { _stack = .; *(.stack) }
   /* These must appear regardless of  .  */
 }

bsps/sh/gensh4/start/linkcmds.rom

@@ -187,7 +187,10 @@ SECTIONS
    __bss_end = .;
   } > ram
 
-  . = ALIGN(16);
+  .rtemsstack (NOLOAD) : {
+    *(SORT(.rtemsstack.*))
+  } > ram
+
   _WorkAreaBase = . ;
 
   . = ALIGN(16);

bsps/sh/gensh4/start/linkcmds.rom2ram

@@ -190,7 +190,10 @@ SECTIONS
       *(.rela.sbss2 .rela.sbss2.* .rela.gnu.linkonce.sb2.*)
       *(.rela.bss .rela.bss.* .rela.gnu.linkonce.b.*)
     } >ram
-  . = ALIGN(16);
+
+  .rtemsstack (NOLOAD) : {
+    *(SORT(.rtemsstack.*))
+  } > ram
 
   _WorkAreaBase = . ;