Add support for FreeBSD/i386 ELF.

Add support for FreeBSD/i386 ELF.
* i386bsd-nat.c: New file.
* config/i386/tm-fbsd.h (HAVE_I387_REGS): Define.
Include "i386/tm-i386.h" instead of "i386/tm-i386b.h".
(NUM_REGS): Remove redefinition.
(USE_STRUCT_CONVENTION): Define.
(i386_float_info): Remove prototype.
(FLOAT_INFO): Remove define.
(JB_ELEMENT_SIZE): Define to 4.
(JB_PC): Define to 0.
(GET_LONGJMP_TARGET): Define.
(SIGTRAMP_START, SIGTRAMP_END): Define.
(SIGCONTEXT_PC_OFFSET): Define.
(IN_SOLIB_CALL_TRAMPOLINE): Only define if !SVR4_SHARED_LIBS
* config/i386/nm-fbsd.h (PTRACE_ARG3_TYPE): Define to caddr_t.
(FETCH_INFERIOR_REGISTERS): Define.
(ATTACH_DETACH): Define.
(kernel_u_size): Remove PARAMS.
(register_u_addr): Use CORE_ADDR in prototype where appropriate.
Remove PARAMS.
(SVR4_SHARED_LIBS) [FREEBSD_ELF || __ELF__ && !FREEBSD_AOUT]:
Define.
[SVR4_SHARED_LIBS]: Include "elf/common.h".
Only define aliases for struct members from <link.h> if
!SVR4_SHARED_LIBS.
* config/i386/xm-fbsd.h: New file.
* config/i386/fbsd.mt (TDEPFILES): Remove solib.o.
* config/i386/fbsd.mh (NATDEPFILES): Remove i386b-nat.o.  Add
core-regset.o i387-nat.o i386bsd-nat.o.