meson: Fix build with MSVC and non-English locale

Otherwise, MSVC will complain and cause build error.
7 jobs for <span class="ref-name">fix-msvc-non-english</span> in 5 minutes and 13 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #308660
build autotools

00:01:36

passed #308661
build meson

00:00:48

 
  Test
passed #308663
distcheck autotools

00:02:56

passed #308665
doc-and-install meson

00:01:02

passed #308662
test autotools

00:01:31

passed #308828
allowed to fail
test meson

00:00:40

failed #308664
allowed to fail
test meson

00:00:45