RFC: drop native (precompiled) support for out-of-fashion 32-bit architectures

[flavorjones]

Proposal

No longer ship native (precompiled) gems for x86-mingw32 or x86-linux platforms in the next Nokogiri minor release (v1.17.x).

Rationale

The architectures x86-mingw32 and x86-linux each account for less than 0.01% of recent Nokogiri gem downloads. Some concrete download stats by version and architecture:

- v1.3 / 2009-05-30:
  - x86-mingw32:         14,993 (11.50%)
- v1.4 / 2009-10-30:
  - x86-mingw32:        143,688 ( 3.82%)
- v1.5 / 2011-07-01:
  - x86-mingw32:      1,011,724 ( 3.99%)
- v1.6 / 2013-06-08:
  - x86-mingw32:      1,742,592 ( 1.49%)
- v1.7 / 2016-12-27:
  - x86-mingw32:        359,806 ( 2.13%)
- v1.8 / 2017-06-05:
  - x86-mingw32:        289,195 ( 0.32%)
- v1.9 / 2018-12-17:
  - x86-mingw32:         56,064 ( 0.77%)
- v1.10 / 2019-01-04:
  - x86-mingw32:        222,421 ( 0.15%)
- v1.11 / 2021-01-04:
  - x86-mingw32:         24,204 ( 0.03%)
  - x86-linux:           19,737 ( 0.03%)
- v1.12 / 2021-08-02:
  - x86-mingw32:         13,598 ( 0.03%)
  - x86-linux:           11,607 ( 0.02%)
- v1.13 / 2022-01-06:
  - x86-mingw32:         17,675 ( 0.02%)
  - x86-linux:           11,919 ( 0.01%)
- v1.14 / 2023-01-12:
  - x86-mingw32:          5,237 ( 0.01%)
  - x86-linux:            4,064 ( 0.01%)
- v1.15 / 2023-05-15:
  - x86-mingw32:          6,755 ( 0.01%)
  - x86-linux:            3,170 ( 0.01%)

These numbers are low enough that they might only be mirrors and bots downloading them.

I'm proposing dropping native (precompiled) support for them both in Nokogiri v1.17.0 which will ship sometime in 2024. Would love to hear reasons for and against.