ld expression parsing changes reverted on 2.37 branch

[Alan Modra]

I have reverted
commit 6afc66a7772e "Re: ld script expression parsing"
commit fb6c220ebdae "ld --defsym"
commit 40726f16a8d7 "ld script expression parsing"
on the binutils-2.37 branch, to fix PR28217 on the branch.

For mainline, I intend to introduce another lexer state to handle
parsing of wildcard file and input section names inside output
sections (and overlays).  That should remove the need to parse
ldgram.y memspec_opt, memspec_at_opt, phdr_opt and fill_opt in
expression mode.  Currently script mode includes the wildcard pattern
which results in, for example, ":text" for a phdr returning one NAME
token rather than the two tokens we want, ":" and a NAME of "text".
I think that will also mean there is no need for ldlex_backup.

-- 
Alan Modra
Australia Development Lab, IBM