sim: Add some methods to create derived symbol tables.
These tables are based on passing the symbols in the current table
through some sort of operator function which can chose to add those
symbols, modified versions of those symbols, or nothing at all into a
new symbol table.
The new table is returned as a shared_ptr so its memory will be
managed automatically.
Change-Id: I8809336e2fc2fda63b16a0400536116ca852ca13
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24786
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>