Avoid PCRE syntax when using grep

Avoid PCRE syntax when using grep because some versions of grep don't
support that.
11 jobs for ryandesign-check-versions in 10 minutes and 17 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Build
passed meson android arm64 fedora #11640388

00:01:34

passed meson macos #11640386
gst-macos-10.15

00:03:24

passed meson-mingw-w64-build #11640383

00:05:33

manual meson msys2 #11640387
docker windows 1809 allowed to fail manual
passed meson-shared-build #11640381

00:05:18

passed meson-static-build #11640382

00:08:10

passed meson vs2017 amd64 #11640384
docker windows 1809

00:01:16

passed meson vs2017 x86 #11640385
docker windows 1809

00:01:20

passed mingw-build #11640380

00:09:04

passed shared-build #11640378

00:10:17

passed static-build #11640379

00:09:23