PR23652, Use symbols from debug bfd for _bfd_elf_find_function properly

PR23652, Use symbols from debug bfd for _bfd_elf_find_function properly

There were a number of problems with the previous patch.  Firstly,
_bfd_dwarf2_stash_syms didn't do anything when the original file had
dynamic symbols, and secondly, info found by the symbol search didn't
make it out of _bfd_elf_find_nearest_line except in the case of DWARF
functions without external linkage.

	PR 23652
	* dwarf2.c (_bfd_dwarf2_stash_syms): Break out of loop on finding
	matching section.
	(_bfd_dwarf2_find_nearest_line): Return an int, with value 2 when
	returning info from the symbol table.  Do the _bfd_elf_find_function
	search also when !found.  Call _bfd_dwarf2_stash_syms regardless of
	symbols.
	* elf64-alpha.c (elf64_alpha_find_nearest_line): Accept dwarf2
	result of 1 only.
	* elfxx-mips.c (_bfd_mips_elf_find_nearest_line): Likewise.
	* libbfd-in.h (_bfd_dwarf2_find_nearest_line): Update prototype.
	* libbfd.h: Regenerate.