meson: do not check for c++

Wayland does not need c++, fixes building with toolchains lacking c++.
3 jobs for meson-cpp in 1 minute and 54 seconds
latest
Status Job ID Name Coverage
  Prep
passed #3860365
debian:buster@container-prep

00:00:32

 
  Build
passed #3860366
build-native-autotools

00:01:21

failed #3860367
build-native-meson

00:00:16

 
Name Stage Failure
failed
build-native-meson Build

A full log can be found at /builds/bkuhls/wayland/build-wayland-1df9b73db6541cbc483c6ee1b21dbe0cb6e5cbfa-3860367/meson-logs/meson-log.txt
Running after_script
Uploading artifacts for failed job
Uploading artifacts...
WARNING: build-meson/meson-logs: no matching files
prefix-*: found 1 matching files

Uploading artifacts to coordinator... ok
id=3860367 responseStatus=201 Created token=61zr6Njs
ERROR: Job failed: exit code 1