move minimal symbols to per-bfd

move minimal symbols to per-bfd

Now that minimal symbols are independent of the program space, we can
move them to the per-BFD object.  This lets us save memory in the
multi-inferior case; and, once the symbol readers are updated, time.

The other prerequisite for this move is that all the objects referred
to by the minimal symbols have a lifetime at least as long as the
per-BFD object.  I think this is satisfied partially by this patch
(moving the copied names there) and partially by earlier patches
moving the demangled name hash.

This patch contains a bit of logic to avoid creating new minimal
symbols if they have already been read for a given BFD.  This allows
us to avoid trying to update all the symbol readers for this
condition.  At first glance this may seem like a hack, but some symbol
readers mix psym and minsym reading, and would require logic just like
this regardless -- and it is simpler and less error-prone to just do
the work in a central spot.

2014-02-26  Tom Tromey  <tromey@redhat.com>

	* minsyms.c (lookup_minimal_symbol, iterate_over_minimal_symbols)
	(lookup_minimal_symbol_text, lookup_minimal_symbol_by_pc_name)
	(lookup_minimal_symbol_solib_trampoline)
	(lookup_minimal_symbol_by_pc_section_1)
	(lookup_minimal_symbol_and_objfile): Update.
	(prim_record_minimal_symbol_full): Use the per-BFD obstack.
	Don't allocate a minimal symbol if minsyms have already been read.
	(build_minimal_symbol_hash_tables): Update.
	(install_minimal_symbols): Do nothing if minsyms already read.
	Use the per-BFD obstack.
	(terminate_minimal_symbol_table): Use the per-BFD obstack.
	* objfiles.c (allocate_objfile): Call
	terminate_minimal_symbol_table later.
	(have_minimal_symbols): Update.
	* objfiles.h (struct objfile_per_bfd_storage) <msymbols,
	minimal_symbol_count, msymbol_hash, msymbol_demangled_hash>:
	Move from struct objfile.
	<minsyms_read>: New field.
	(struct objfile) <msymbols, minimal_symbol_count,
	msymbol_hash, msymbol_demangled_hash>: Move.
	(ALL_OBJFILE_MSYMBOLS): Update.
	* symfile.c (read_symbols): Set minsyms_read.
	(reread_symbols): Update.
	* symmisc.c (dump_objfile, dump_msymbols): Update.