Align _end symbol to at least 4 in all MIPS scripts

Left-over part of commit 84b2a020da

The _end marker must be aligned to 4-bytes to ensure that the last
element written does not reach beyond the address of _end.  This is
also necessary as the termination condition is an equality test
instead of an ordered test so (_end - _fbss) must be a multiple of
4-bytes.  The alignment is already correct for mti*.ld files, fix
it for all remaining MIPS scripts that don't already align to at
least 4.

libgloss/mips/jmr3904app-java.ld

@@ -99,6 +99,7 @@ SECTIONS
     . = __stack ;
   }
 
+  . = ALIGN(4);
    end = .;
    _end = .;