Fix the toolchain madness

[prasannavl]

Summary

• The largest headaches in the toolchain is often due to the way depends overrides the toolchains
  • For darwin cross compiles it hijacks the compilers entirely
  • For the others, it reuses the env compilers
• Rust and cargo ecosystem will attempt to compile it's native libraries on it's own which will result in calling C/XX compilers resulting in nested compilation env that are highly inconsistent since depends simply overrides it.
• This is further made challenging since some Rust libs will require host builds (eg: build-deps), while some require target builds.
• This retains the overrides from depends and passes it along cleanly in an attempt to resolve this madness.

Additional

• ./make.sh respects CC and CXX vars and will not override them
• MAKE_USE_CLANG is auto set based on basic heuristics and can now be easily switched off
• solc:
  • Adds solc to depends system
  • Exports SOLC_PATH var for solc bin path
  • References:
    • https://docs.soliditylang.org/en/latest/installing-solidity.html#static-binaries
    • Repo structure: https://github.com/ethereum/solc-bin/

Implications

• Storage

  • Database reindex required
  • Database reindex optional
  • Database reindex not required
  • None

• Consensus

  • Network upgrade required
  • Includes backward compatible changes
  • Includes consensus workarounds
  • Includes consensus refactors
  • None