gdb/dwarf: move cooked_indexer to cooked-indexer.{h,c}

Move the cooked_indexer class declaration to a new cooked-indexer.h
file, and the implementation to cooked-indexer.c.

Change-Id: Ibff3b06045b2af65fa9516097acf732d7c2d9414
Approved-By: Tom Tromey <tom@tromey.com>
5 files changed