Always set up sh_name in assign_section_numbers

Always set up sh_name in assign_section_numbers

commit 9ad5cbcfb23cb74d34bd04f88f4e47c0f5de5155 added the initial support
for more than 64k ELF sections with holes for reserved section indices in
section header table and set entries of reserved section indices in
section header table to index 0:

   for (secn = 1; secn < section_number; ++secn)
-    i_shdrp[secn]->sh_name = _bfd_elf_strtab_offset (elf_shstrtab (abfd),
-                                                    i_shdrp[secn]->sh_name);
-
+    if (i_shdrp[secn] == NULL)
+      i_shdrp[secn] = i_shdrp[0];
+    else
+      i_shdrp[secn]->sh_name = _bfd_elf_strtab_offset (elf_shstrtab (abfd),
+							i_shdrp[secn]->sh_name);

commit 4fbb74a6055f7d48f09c44064073d3b1e99c6642 removed holes in section
header table.  Check for i_shdrp[secn] == NULL is no longer needed now.
This patch removes it.

	* elf.c (assign_section_numbers): Always set up sh_name.