Ignore Meson subprojects with .gitignore

Meson projects using Meson subprojects have a project directory structure like:

meson.build
main.c
subprojects/
  lapack/
  lapack.wrap

where “subprojects/lapack/” is automatically created as a Meson subproject from the metadata in “subprojects/lapack.wrap”. Using the negate .gitignore syntax Git will ignore subdirectories but track the subprojects/*.wrap files:

include in the project .gitignore:

subprojects/

!subprojects/*.wrap

This technique can be applied to similar non-Meson scenarios.