Bump LLVM version and fix aflpp version and apply patches

[tokatoka]

Right now, we cannot use clang-20 and future versions because AFL++ forces to add "-flto" flag when there is "-fcf-protection"
bitcoin/bitcoin#31913 (comment)

we can

1. fix the version of AFL++ that we use, and
2. patch AFL++ before building the docker images
   to mitigate this issue.

[dergoegge]

Have you tried using -O1. I'd prefer not having to patch afl++

[tokatoka]

Have you tried using -O1. I'd prefer not having to patch afl++

it doesn't work either

the real problem in AFL++ is here
https://github.com/AFLplusplus/AFLplusplus/blob/afbcb07e7602791390adfc63932efcd14d39bab8/instrumentation/SanitizerCoveragePCGUARD.so.cc#L234
The compiler pass just don't instrument anything at all if we are using -flto (which we are forced to, because -fcf-protection always comes with -flto in AFL++ without patch