Rewrite FreeBSD/sparc64 native configuration.

Rewrite FreeBSD/sparc64 native configuration.
* sparcbsd-nat.c, sparcbsd-nat.h: New files.
* sparc64fbsd-nat.c: New file.
* sparc64fbsd-tdep.c: New file.
* sparc64-tdep.c sparc64-tdep.h: New files.
* Makefile.in (sparcbsd-nat.o, sparc64fbsd-nat.o, sparc64-tdep.o,
sparc64fbsd-tdep.o): New dependencies.
(SFILES): Add sparcbsd-nat.c, sparc64fbsd-nat.c, sparc64-tdep.c
and sparc64fbsd-tdep.c.
(sparc64_tdep_h, sparcbsd_nat_h): New variables.
* config/sparc/fbsd.mh: Remove copyright notice.
(NATDEPFILES): Remove sparc-nat.o, add sparc64fbsd-nat.o and
sparcbsd-nat.o.
* config/sparc/fbsd.mt: Remove copyright notice.
(TDEPFILES): Remove sparc-tdep.o, solib.o solib-svr4.o,
solib-legacy.o.  Add sparc64-tdep.o and sparc64fbsd-tdep.o.
* config/sparc/nm-fbsd.h: Don't include "elf/common.h".
(SVR4_SHARED_LIBS, PTRACE_GETREGS, PTRACE_SETREGS,
PTRACE_GETFPREGS, PTRACE_SETFPREGS, GDB_GREGSET_T, GDB_FPREGSET_T,
regs, r_g1, r_ps, r_pc, r_npc, r_y, FPU_FSR_TYPE, fp_status, fpu,
fpu_regs, fp_fr, fpu_fsr, Fpu_fsr): Remove defines.
* config/sparc/tm-fbsd.h: Don't include "solib.h" and
"sparc/tm-sp64.h".
(SVR4_SHARED_LIBS, START_INFERIOR_TRAPS_EXPECTED): Remove defines.
(GDB_MULTI_ARCH): Define to GDB_MULTI_ARCH_TM.