[clang] [clang-format] Add SpaceBeforeUnderscoreParens option for GNU gettext… (PR #159925)

[Björn Schäpers via cfe-commits]

https://github.com/HazardyKnusperkeks commented:

How do you want it to do without an option? Just never adding a space between `_` and `(` might not be the thing somebody else wants.

https://github.com/llvm/llvm-project/pull/159925