x86: Allow configuring with --with-arch_64=x86-64-v[234]

x86: Allow configuring with --with-arch_64=x86-64-v[234]

> +  {"x86-64", PROCESSOR_K8, CPU_K8, PTA_X86_64_BASELINE, 0, P_NONE},
> +  {"x86-64-v2", PROCESSOR_K8, CPU_GENERIC, PTA_X86_64_V2 | PTA_NO_TUNE,
> +   0, P_NONE},
> +  {"x86-64-v3", PROCESSOR_K8, CPU_GENERIC, PTA_X86_64_V3 | PTA_NO_TUNE,
> +   0, P_NONE},
> +  {"x86-64-v4", PROCESSOR_K8, CPU_GENERIC, PTA_X86_64_V4 | PTA_NO_TUNE,
> +   0, P_NONE},
>    {"eden-x2", PROCESSOR_K8, CPU_K8,
>      PTA_64BIT | PTA_MMX | PTA_SSE | PTA_SSE2 | PTA_SSE3 | PTA_FXSR,
>      0, P_NONE},

I have noticed that one can't configure gcc to default to these.

I've also found various other 32-bit or 64-bit -march= arguments for which
it wasn't possible to configure gcc to default to those.

The x86-64-v* the patch only allows in --with-arch_64=, because otherwise
it fails build miserably - as
./xgcc -B ./ -S -march=x86-64-v2 -m32 test.c
cc1: error: ‘x86-64-v2’ architecture level is only defined for the x86-64 psABI
when building 32-bit multilibs.  Even if multilibs are disallowed, I think
the compiler still supports -m32 and so --with-arch_64= seems to be the only
option in which we can support that.

2020-10-22  Jakub Jelinek  <jakub@redhat.com>

	* config.gcc (x86_archs): Add samuel-2, nehemiah, c7 and esther.
	(x86_64_archs): Add eden-x2, nano, nano-1000, nano-2000, nano-3000,
	nano-x2, eden-x4, nano-x4, x86-64-v2, x86-64-v3 and x86-64-v4.
	(i[34567]86-*-* | x86_64-*-*): Only allow x86-64-v* as argument
	to --with-arch_64=.