Revert previous change. It doesn't work because it neglects to

Revert previous change.  It doesn't work because it neglects to
consider there may be a file compiled without -g screwing things up
(e.g. we are looking for the minimal symbol for "main" and we get the
one for "start" instead).

This is the change I mean:
	* minsyms.c, symtab.h (lookup_next_minimal_symbol): New function.
	* dbxread.c (process_one_symbol): Use it.