gdb/dwarf: remove create_cu_from_index_list

I noticed that create_cu_from_index_list is only used in
read-gdb-index.c, so I started by moving it there.  But given that this
function is use at only one spot and doesn't do much, I opted to inline
its code in the caller instead.

Change-Id: Iebe0dc20d345fa70a2f11aa9ff1a04fe26a31407
Approved-By: Tom Tromey <tom@tromey.com>
3 files changed