add TLS support on score binutils

[brain dot lin at sunplusct dot com]

Hi Nick,
 I encountered some problem need your help when i added the  TLS (Thread 
Local Storage) on score binutls. as followings:
 
  One score relocation type need two got entry, I attempted add the 
elf_hash_table (info)->dynsymcount + 2. but the result is error.
  I found the struct elf_link_hash_entry  has the similar usage.as 
followings,but i don't know how to use it .I need your help.

  Thanks,All the best.

 /* If this symbol requires an entry in the global offset table, the
     processor specific backend uses this field to track usage and
     final offset.  Two schemes are supported:  The first assumes that
     a symbol may only have one GOT entry, and uses REFCOUNT until
     size_dynamic_sections, at which point the contents of the .got is
     fixed.  Afterward, if OFFSET is -1, then the symbol does not
     require a global offset table entry.  The second scheme allows
     multiple GOT entries per symbol, managed via a linked list
     pointed to by GLIST.  */
  union gotplt_union
    {
      bfd_signed_vma refcount;
      bfd_vma offset;
      struct got_entry *glist;
      struct plt_entry *plist;
    } got;