PATCH [1/n]: Add initial -x32 support

[Joseph S. Myers]

On Sun, 5 Jun 2011, H.J. Lu wrote:

> 	* config.gcc: Support --enable-x32/--enable-ia32 for x86 Linux
> 	targets.
> 
> 	* configure.ac: Support --enable-x32/--enable-ia32.
> 	* configure: Regenerated.

New configure options need documenting in install.texi.

>  #undef ASM_SPEC
> -#define ASM_SPEC "%{" SPEC_32 ":--32} %{" SPEC_64 ":--64} \
> +#define ASM_SPEC "%{" SPEC_32 ":%{!mx32:--32}} %{" \
> + SPEC_64 ":%{!mx32:--64}} %{mx32:--x32} \
>   %{!mno-sse2avx:%{mavx:-msse2avx}} %{msse2avx:%{!mavx:-msse2avx}}"

This looks wrong.  You should define SPEC_32, SPEC_64 and SPEC_X32 to be 
the three mutually exclusive cases, then use those three here and in other 
specs without any nesting.

>  Generate code for a 32-bit or 64-bit environment.
> -The 32-bit environment sets int, long and pointer to 32 bits and
> +The -m32 option sets int, long and pointer to 32 bits and

@option{-m32}.  Likewise later in this paragraph for various option names.

-- 
Joseph S. Myers
joseph@codesourcery.com