meson: Look for FreeType using CMake too

Some systems build FreeType using CMake rather than autotools (such as Visual
Studio), which will give us CMake config files rather than pkg-config files, so
if we can't find FreeType using pkg-config, try again using CMake.

Please note that according to FreeType's docs/VERSIONS.TXT, the version we want
when checking with CMake is 2.8.1 or later.
10 jobs for ft.cmake in 7 minutes and 22 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #4801120
gst-macos-10.15
meson macos

00:00:52

passed #4801117
meson-mingw-w64-build

00:04:51

manual #4801121
docker windows 1809 allowed to fail manual
meson msys2
passed #4801115
meson-shared-build

00:04:55

passed #4801116
meson-static-build

00:05:53

passed #4801118
docker windows 1809
meson vs2017 amd64

00:01:09

passed #4801119
docker windows 1809
meson vs2017 x86

00:01:09

passed #4801114
mingw-build

00:06:29

passed #4801112
shared-build

00:07:22

passed #4801113
static-build

00:06:20