Problem:
Missing libthread_db integration with GDB

Cause:
GDB missing libthread_db integration on FreeBSD target because of this
GDB failed to access TLS variable values.

Tests failed:
- gdb.threads/tls-shared.exp
- gdb.threads/tls-nodebug-pie.exp
- gdb.threads/tls-so_extern.exp
- gdb.threads/tls-var.exp
- gdb.threads/tls.exp
- gdb.threads/tls-core.exp

gdb/ChangeLog:
2018-09-15  Rajendra SY  <syrajendra@juniper.net>

       PR gdb/23660
       * gdb/amd64-fbsd-nat.c (supply_gregset):
        (fill_gregset):
        (supply_fpregset):
        (fill_fpregset):
        * gdb/amd64-fbsd-tdep.c (amd64fbsd_init_abi):
        * gdb/configure.nat:
        * gdb/fbsd-thread-db.c: New file.
        * gdb/i386-bsd-nat.c (supply_gregset):
        (supply_fpregset):
        (fill_gregset):
        (fill_fpregset):
        * gdb/i386-fbsd-tdep.c (i386fbsd4_init_abi):