Upgrade initial GCC build from 4.0.4 to Ekaitz's 4.6.4.1

[Googulator]

We currently build GCC 4.0.4 with TCC in Fiwix. This version has limited support for non-x86 architectures (no RISC-V, no ARM64, etc.), and also limits what kernel versions we can build.

As part of his Guix RISC-V bootstrap effort, Ekaitz Zárraga has made a fork of GCC 4.6 (https://github.com/ekaitz-zarraga/gcc), adding support for RISC-V code generation, and making it buildable with TCC. This version has been informally named "4.6.4.1". This newer GCC gives us a chance to upgrade the Linux kernel at least to 4.19, which is supported at least until 2029 by the CIP Project.

[nanonyme]

I'm not honestly sure whether that would be more or less risky than using long EOL GCC. Seems presuming there is clear auditable commit trail from GCC fork point, biggest issue seems whether you can rely in it to not stop existing.

[fosslinux]

My viewpoint is that having x86-only is worse longterm and we need this to do anything about that. I don't see the fork going anywhere, it seems materially complete. It is more risky than EOL GCC, but not significantly so, in my viewpoint.

Here, worst case is the patches with git-format-patch from GCC 4.6. "Only" 18k lines. Which is less than I expected to be honest.

gcc-4.6.4.1-git-format-patches.tar.gz