Unwrap symbols for debug information

Fixes issues with dwz multi-file (-m) and ld's -wrap option.
Symbols referenced from DWARF debug info in a separate file, eg. to
specify low and high pc, must use the real symbol.  The DWARF info
is specifying attributes of the real function, not one interposed
with --wrap.

include/
	* bfdlink.h (unwrap_hash_lookup): Declare.
bfd/
	* linker.c (unwrap_hash_lookup): New function.
	* elf-bfd (RELOC_FOR_GLOBAL_SYMBOL): Call unwrap_hash_lookup.
	* elf32-i370.c (i370_elf_relocate_section): Likewise.
	* elf32-m32c.c (m32c_elf_relocate_section): Likewise.
	* elf32-m32r.c (m32r_elf_relocate_section): Likewise.
	* elf32-score.c (s3_bfd_score_elf_relocate_section): Likewise.
	* elf32-score7.c (s7_bfd_score_elf_relocate_section): Likewise.
	* elf32-spu.c (spu_elf_relocate_section): Likewise.
	* elf64-hppa.c (elf64_hppa_relocate_section): Likewise.
missing changelog entries for 8a5da09b9
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