* symtab.c, symtab.h, source.c: Change find_line_pc_range to take

	* symtab.c, symtab.h, source.c: Change find_line_pc_range to take
	a struct symtab_and_line argument, rather than a symtab and a line.
	Re-write it to be based on the address rather than bogusly adding
	one to the line number and hoping that has something to do with the
	end of the line.