Use std::sort instead of qsort in minsyms.c
    
    This has better typesafety and is also marginally faster (either
    due to inlining or because it avoids indirection through a
    function pointer).
    
    Note that in this change:
    -       return 1;               /* fn1 has no name, so it is "less".  */
    +       return true;            /* fn1 has no name, so it is "less".  */
           else if (name1)          /* fn2 has no name, so it is "less".  */
    -       return -1;
    +       return false;
    I am fairly sure the old code was wrong (ie. code didn't match the
    comment and the comment seemed correct), so I fixed it.
    
    gdb/ChangeLog:
    
    2019-09-28  Christian Biesinger  <cbiesinger@google.com>
    
    	* minsyms.c (compare_minimal_symbols): Rename to...
    	(minimal_symbol_is_less_than): ...this, and adjust to STL
    	conventions (return bool, take arguments as references)
    	(minimal_symbol_reader::install): Call std::sort instead
    	of qsort.