New review comment by atweiden on void-packages repository

https://github.com/void-linux/void-packages/pull/38916#discussion_r955913776

Comment:
I recall builds failing without `CXX_FLAGS="-pthread"` [here](https://github.com/JamiKettunen/void-packages/pull/1/commits/ffb2da4ad9046b31af3d4b599173287351b8cc3f#diff-bca5da9ef6beabdb4b700bca6f48e8bc58ebe29fb8c5a6ac5d02978daa7de000R22).