Resync libiberty sources with master version in GCC repository.
    
    2018-04-13  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
    
    	PR lto/81968
    	* simple-object.c (handle_lto_debug_sections): Keep .comment
    	section.
    
    2018-03-02  David Malcolm  <dmalcolm@redhat.com>
    
    	* cp-demangle.c: Update URL for g++ V3 ABI.
    
    2018-01-20  Eli Zaretskii  <eliz@gnu.org>
    
    	* simple-object-xcoff.c (simple_object_xcoff_find_sections): Use
    	ulong_type to avoid warning about 32-bit shift.
    
    2018-01-11  Richard Biener  <rguenther@suse.de>
    	Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
    
    	PR lto/81968
    	* simple-object-common.h (struct simple_object_functions):
    	Change copy_lto_debug_sections callback signature.
    	* simple-object-elf.c (SHN_HIRESERVE, SHT_SYMTAB_SHNDX,
    	SHF_INFO_LINK): Add defines.
    	(simple_object_elf_copy_lto_debug_sections): Instead of
    	leaving not to be copied sections empty unnamed SHT_NULL
    	remove them from the target section headers and adjust section
    	reference everywhere.  Handle SHN_XINDEX in the symbol table
    	processing properly.
    	* simple-object.c (handle_lto_debug_sections): Change
    	interface to return a modified string and handle renaming
    	of relocation sections.
    
    2018-01-10  Daniel van Gerpen  <daniel@vangerpen.de>
    
    	* argv.c (expandargv): Correct check for dynamically
    	allocated argv.