* configure.tgt: Add back sparc-*-vxworks*.

* configure.tgt: Add back sparc-*-vxworks*.
* remote-vxsparc.c: Remove all includes except for "defs.h",
"regcache.h", "vx-share/ptrace.h" and "vx-share/regPacket.h".
Include "sparc-tdep.h".
(SPARC_R_G1): New define.
(vxsparc_gregset): New variable.
(ext_format_sparc): Remove extern declaration.
(vx_read_register): Rewrite to use sparc32_supply_gregset and
sparc32_supply_fpregset.
(vx_write_register): Rewrite to use sparc32_collect_gregset,
sparc_collect_rwindow and sparc32_collect_fpregset.
* config/sparc/tm-vxworks.h: New file, based on recently removed
tm-vxsparc.h.
* config/sparc/vxworks.mt: New file, based on recently removed
vxworks.mt.