MFC r295901:

Fix a problem in ld, causing it to sometimes print messages similar to
"invalid string offset 65521 >= 27261 for section `.strtab'". for object
files produced by recent versions of clang.

In BFD's elf_create_symbuf() function, the size of the symbol buffer
('ssymbuf') is not calculated correctly, and the initial value for the
'ssym' variable is off by one, since 'ssymbuf' has shndx_count + 1
members.