Clean up ARM string option handling

This patch cleans up ARM handling of various options, making
enumerated options that were handled in arm_option_override use Enum
instead (except for -mfpu=, to be handled in a subsequent patch) and
using UInteger for -mstructure-size-boundary=.

-mfp= and -mfpe= (legacy aliases) are converted into actual .opt Alias
entries for each valid argument to those options.  (Thus, the last of
a sequence of interspersed -mfpu= and -mfp=/-mfpe= options now wins,
which I think is correct, whereas previously an earlier -mfpu= option
would override a later -mfp=/-mfpe= option.)
-mstructure-size-boundary= using UInteger means that its arguments are
now required to be decimal integers without leading whitespace or
ignored trailing text, whereas previously such variants (and octal and
hexadecimal values) would be accepted; I think this stricter checking,
consistent with other integer-valued options, is also the desired
semantics.

Tested building cc1 and xgcc for cross to arm-eabi.  Will commit to
trunk in the absence of target maintainer objections.

Remarks on oddities in the configuration of various ARM targets for
the consideration of the ARM target maintainers (I don't plan to work
on these issues):

* The default float-abi (TARGET_DEFAULT_FLOAT_ABI) is "hard" only for
  old-ABI GNU/Linux.  Although it's also defined to ARM_FLOAT_ABI_HARD
  in arm/semi.h, that definition gets overridden in arm/coff.h.

* The header arm/aout.h has a comment saying it is for "ARM with
  a.out", which is misleading since there are no such targets in GCC.
  Actually, all ARM targets include it either immediately before
  arm/arm.h, or in the case of FreeBSD with arm/freebsd.h inbetween -
  but arm/freebsd.h does not test or modify any macros from
  arm/aout.h, so actually arm/aout.h could safely be merged into
  arm/arm.h, making the port simpler and less confusing.  (I haven't
  checked whether arm/arm.h tests or modifies any macros from
  arm/aout.h, which would be relevant to determining the best way to
  merge each macro into arm/arm.h.)

* The header arm/semi.h says "ARM on semi-hosted platform" - which is
  also misleading since it's only used for WinCE.  As noted above at
  least one target macro in this header is dead.  As the four headers
  arm/semi.h arm/coff.h arm/pe.h arm/wince-pe.h are all only used for
  this one target, and I doubt the distinctions between them genuinely
  follow any proper abstraction levels between four different sets of
  targets that simply happen to be the same right now, merging them
  into one header might improve things.

* arm*-*-uclinux* are legacy Linux-based targets not using the common
  gnu-user.h and linux.h headers as they should be.

* There were previous discussions of deprecating at least some
  non-AAPCS targets.  Since for some target OSes (such as WinCE) the
  ABI is what it is, it may not be possible to eliminate the old ABI
  support completely.  But maybe some other OS maintainers (VxWorks,
  FreeBSD, NetBSD, eCos, RTEMS) are moving their OSes to use AAPCS, in
  which case some older target variants could be deprecated and
  removed?  (Maybe old-ABI bare-metal, GNU/Linux and uClinux could be
  deprecated in any case.)  Closely tied into old-ABI use are defaults
  of -mfpu= based on the selected CPU - but NetBSD and VxWorks at
  least default to VFP (define FPUTYPE_DEFAULT appropriately) even
  though using pre-AAPCS ABIs.

* There was also a previous suggestion that -mwords-little-endian is
  long-obsolete and should be removed as well.

2011-05-17  Joseph Myers  <joseph@codesourcery.com>

	* config/arm/arm-opts.h (enum arm_fp16_format_type, enum
	arm_abi_type, enum float_abi_type, enum arm_tp_type): Move from
	arm.h.
	* config/arm/arm.c (arm_float_abi, arm_fp16_format, arm_abi,
	target_thread_pointer, arm_structure_size_boundary, struct
	float_abi, all_float_abis, struct fp16_format, all_fp16_formats,
	struct abi_name, arm_all_abis): Remove.
	(arm_option_override) Don't process most enumerated option values
	here.  Don't process target_fpe_name here.  Work with integer not
	string for structure size boundary; use separate diagnostics for
	each case.
	* config/arm/arm.h (enum float_abi_type, enum
	arm_fp16_format_type, enum arm_abi_type, enum arm_tp_type): Move
	to arm-opts.h.
	(arm_float_abi, arm_fp16_format, arm_abi, target_thread_pointer,
	arm_structure_size_boundary): Remove.
	* config/arm/arm.opt (mabi=): Use Enum and Init.
	(arm_abi_type): New Enum and EnumValue entries.
	(mfloat-abi=): Use Enum and Init.
	(float_abi_type): New Enum and EnumValue entries.
	(mfp=, mfpe=): Replace by separate Alias entries for each
	argument.
	(mfp16-format=): Use Enum and Init.
	(arm_fp16_format_type): New Enum and EnumValue entries.
	(mstructure-size-boundary=): Use UInteger and Init.
	(mtp=): Use Enum and Init.
	(arm_tp_type): New Enum and EnumValue entries.

Clean up ARM string option handling

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