* tc-m68k.c (flag_reg_prefix_optional): New variable. Initialized to value of

* tc-m68k.c (flag_reg_prefix_optional): New variable.  Initialized to value of
REGISTER_PREFIX_OPTIONAL, if defined, or zero.
(m68k_reg_parse): If flag_reg_prefix_optional is set, permit register prefix to
be absent.
(m68k_ip_op): Accept `&' also for immediate constants.
(insert_reg): Don't bother with (two!?) sanity checks of the symbol table when
inserting each register.
(m68k_parse_long_option): New function.  Set flag_reg_prefix_optional if
"register-prefix-optional" is passed.
* tc-m68k.h (REGISTER_PREFIX): Always define if not already defined.
(OPTIONAL_REGISTER_PREFIX): Don't define.
(REGISTER_PREFIX_OPTIONAL): If not already defined, define as zero
or one depending on M68KCOFF.

Some changes to help Apollo support, from troy@cbme.unsw.edu.au:
* tc-m68k.c (DATA, ADDR, SP, FPREG, COPNUM, BAD, BAC): Define as macros instead
of enumerators, since the Apollo compiler can't handle "enumVal1, enumVal2 =
enumVal1" when defining an enum type.
(make_pcrel_absolute) [NO_PCREL_RELOCS]: New function.
(tc_coff_fix2rtype) [NO_PCREL_RELOCS]: Generate only R_RELBYTE, R_DIR16, and
R_DIR32 relocs.
* tc-m68k.h [TE_APOLLO] (COFF_MAGIC, COFF_AOUTHDR_MAGIC): Use Apollo versions.
[TE_APOLLO] (OBJ_COFF_OMIT_OPTIONAL_HEADER): Undefine.  That is, do include the
optional header for Apollo target.
(COFF_MAGIC): Don't define as MC68MAGIC if it's already defined.

* tc-m68k.h [TE_DELTA] (LEX_PCT): Define as 1, so that `%' can be used within a
label name.

* tc-m68k.h (m68k_init_after_args): Declare.
(tc_init_after_args): Define as m68k_init_after_args.
* tc-m68k.c (m68k_init_after_args): New function, containing one-shot code from
md_assemble.  Added warning for combination of 68040 and 68851.
(md_assemble): Startup-time code deleted.