a file, once a new symtab has been read for it.
* symtab.h (GLOBAL_BLOCK, STATIC_BLOCK, FIRST_LOCAL_BLOCK): New
defines for the blocks of a blockvector that contain global and
file-static symbols and the first of the smaller scope contours.
* symtab.c (lookup_symbol, find_pc_symtab, find_pc_line,
decode_line_1, make_symbol_completion_list): Use the above.
* coffread.c (end_symtab, patch_opaque_types): Ditto.