Remove too-tricky make_lisp_symbol optimization

Remove too-tricky make_lisp_symbol optimization

Simplify optimization for make_lisp_symbol, so that
it’s less tricky and works well enough for gcc -Og or -O2.
* src/lisp.h (lisp_h_builtin_lisp_symbol): Remove.
(builtin_lisp_symbol) [DEFINE_KEY_OPS_AS_MACROS]: Remove.
(make_lisp_symbol_nodebug): New internal static function,
which is like the old make_lisp_symbol but without the eassert.
(make_lisp_symbol, builtin_lisp_symbol): Use it, so that
make_lisp_symbol has the eassert but builtin_lisp_symbol doesn’t.
Co-authored-by: Paul Eggert <eggert@cs.ucla.edu>