Defer minimal symbol name-setting
    
    Currently the demangled name of a minimal symbol is set when creating
    the symbol.  However, there is no intrinsic need to do this.  This
    patch instead arranges for the demangling to be done just before the
    minsym hash tables are filled.  This will be useful in a later patch.
    
    gdb/ChangeLog
    2019-09-30  Tom Tromey  <tom@tromey.com>
    
    	* symtab.h (struct minimal_symbol) <name_set>: New member.
    	* minsyms.c (minimal_symbol_reader::record_full): Copy name.
    	Don't call symbol_set_names.
    	(minimal_symbol_reader::install): Call symbol_set_names.