Make SeaBIOS reproducible across different toolchain versions

[pietrushnic]

As of version 2024-03-30_cccada28f7, SeaBIOS is sensitive to information about the toolchain, which leads to a lack of reproducibility across toolchain versions (we are talking here coreboot-sdk/dasharo-sdk). The following log comes from building SeaBIOS using two different toolchains.

3107c3122
< #define BUILD_TOOLS "gcc: (coreboot toolchain v2024-03-30_cccada28f7) 13.2.0 binutils: (GNU Binutils) 2.42"
---
> #define BUILD_TOOLS "gcc: (coreboot toolchain v2024-02-18_732134932b) 13.2.0 binutils: (GNU Binutils) 2.41"

[pietrushnic]

The question is its importance; according to reproducible builds, the number of attributes related to the built environment should be limited. The lack of a reproducible build environment is a significant issue here because we cannot be sure that we will get the same build environment in the future; for now, we are relying on the fact that Dockerhub hosts coreboot-sdk images.

What can we do here?

• We can limit information about the toolchain to compiler and binutils versions, mentioning this is the coreboot toolchain.
• We may assume that information about the toolchain version is vital to make binaries reproducible.