VMS-specific scope fix for S_mayberelocate.

VMS-specific scope fix for S_mayberelocate.

Back in 3185893b8dec106 I moved some code from the beginning of one
block to the middle of a different block.  Bad me.  The compiler
has been lax about allowing declarations in the middle of a block,
so we haven't noticed.  But as of c29067d7797853039, the code moved
to a new function while leaving the block it was in behind and we
end up with conflicting declarations of len.

Making our own block seems like the safest thing to do.  The
indentation in this section of code is a bit wacky -- I chose the
least intrusive alternative for clearer blame logs.