* gdbtypes.c (make_{reference,pointer,function}_type): New

* gdbtypes.c (make_{reference,pointer,function}_type):  New
functions which handle overwriting of forward-referenced types
for stabs file reading.
(lookup_{reference,pointer,function}_type):  These just call
the make_*_type functions with a null storage alloc parameter.
* gdbtypes.h (make_{reference,pointer,function}_type):  Declare.
* xcoffread.c (smash_to_pointer_type):  Remove, no longer used.

* buildsym.c (dbx_lookup_type):  Zero result for (-1,-1) arg.
(dbx_alloc_type):  Make it easier to understand.  No funct change.
(define_symbol: 't'):  Don't put the typedef name into the name of
the struct, union, or enum.  Bugfix.
(read_type: '*', '&', 'f'):  Add comments.  Use make_XXX_type
routines to properly handle overwriting preallocated types so that
forward references will work.
(read_enum_type):  Force enum values to file scope, due to bug in
Sun compiler output.  FIXME, fix later.

Remove unused header_file_prev_index mechanism.  It was already
obsolete in gdb-3.5.  These comments appeared in 3.5:
  /* This code was used before I knew about the instance codes.
     My first hypothesis is that it is not necessary now
     that instance codes are handled.  */
* dbxread.c (add_new_header_file):  Remove header_file_prev_index.
* buildsym.h:  Remove it and prev_index that saves it.
* buildsym.c (push_subfile, pop_subfile, start_symtab):  Remove it.

* solib.c (special_symbol_handling):  When called from core files,
must set up debug_addr.  Don't print error messages, just return.
* symmisc.c (print_symbol):  Less ascii diarrhea for enums, please.