Do not capture updated 'pc' in add_local_symbols

Simon pointed out that commit 13835d88 ("Use function view when
iterating over block symbols") caused a regression.  The bug is that
the new closure captures 'pc' by reference, but later code updates
this variable -- but the earlier code did not update the callback
structure with the new value.

This patch restores the old behavior by using a new varible name in an
inner scope.