Need local github mirrors for non-github repos

[buzmeg]

When trying to build, I get quite a few timeouts from various non-Github repositories like this:

Setting up /work/_builds/linux-x64/cvc4/cvc4/deps/antlr-3.4/libantlr3c-3.4 ...
--2025-08-22 23:33:44--  https://www.antlr3.org/download/C/libantlr3c-3.4.tar.gz
Resolving www.antlr3.org (www.antlr3.org)... 185.199.109.153, 185.199.110.153, 185.199.108.153, ...
Connecting to www.antlr3.org (www.antlr3.org)|185.199.109.153|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 546039 (533K) [application/gzip]
Saving to: 'archive'

     0K .......... .......... .......... .......... ..........  9% 6.73M 0s
    50K .......... .......... .......... .......... .......... 18% 8.20M 0s
   100K .......... .......... .......... .......... .......... 28% 36.9M 0s
   150K .......... .......... .......... .......... .......... 37% 34.3M 0s
   200K .......... .......... .......... .......... .......... 46% 12.6M 0s
   250K .......... .......... .......... .......... .......... 56% 41.0M 0s
   300K .......... .......... .......... .......... .......... 65% 57.8M 0s
   350K .......... .......... .......... .......... .......... 75%  102M 0s
   400K .......... .......... .......... .......... .......... 84% 37.0M 0s
   450K .......... .......... .......... .......... .......... 93% 19.4M 0s
   500K .......... .......... .......... ...                  100% 7.30M=0.03s

2025-08-22 23:33:44 (17.0 MB/s) - 'archive' saved [546039/546039]

--2025-08-22 23:33:44--  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
Resolving git.savannah.gnu.org (git.savannah.gnu.org)... 209.51.188.168, 2001:470:142::168
Connecting to git.savannah.gnu.org (git.savannah.gnu.org)|209.51.188.168|:80... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: https://gitweb.git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD [following]
--2025-08-22 23:33:45--  https://gitweb.git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
Resolving gitweb.git.savannah.gnu.org (gitweb.git.savannah.gnu.org)... 38.102.85.135, 135.148.138.35, 2604:2dc0:101:200::1c35, ...
Connecting to gitweb.git.savannah.gnu.org (gitweb.git.savannah.gnu.org)|38.102.85.135|:443... connected.
HTTP request sent, awaiting response... 502 Bad Gateway
2025-08-22 23:34:45 ERROR 502: Bad Gateway.

Presumably in this world of bots run amok, these repos should be periodically read-only mirrored on Github so that building oss-cad-suite doesn't overrun less well-equipped projects.

Thanks.