This changes add_psymbol_to_list to use an enum, rather than a pointer
to a vector, to decide where to put the new symbol. This reduces the
number of direct references to the static_psymbols and global_psymbols
members of the objfile, which is handy in a later patch.
gdb/ChangeLog
2019-01-10 Tom Tromey <tom@tromey.com>