* symfile.h (allocate_symtab): Update.
* symfile.c (allocate_symtab): Make 'filename' const.
* psymtab.c (add_psymbol_to_bcache): Make 'name' const.
(add_psymbol_to_list): Likewise.
* psympriv.h (struct partial_symtab) <filename, dirname>: Now
const.
(add_psymbol_to_list): Update.
* mdebugread.c (new_symtab): Make 'name' const.
(psymtab_to_symtab_1): Make 'filename' const.
* elfread.c (elfstab_offset_sections): Update.
* dwarf2read.c (dwarf_decode_lines): Make 'comp_dir' const.
(dwarf2_start_subfile): Make 'dirname' and 'comp_dir' const.
(psymtab_include_file_name): Update.
* dbxread.c (find_stab_function_addr): Make 'filename' const.
* buildsym.h (start_subfile): Update.
* buildsym.c (start_subfile): Make arguments const.