meson: add check kwarg to run_command

run_command will change the default for the check arg to true
in the future. If it is true then meson will exit if the command
fails. It must be false here as we check the return code to
provide a meaningful error message.

With meson 0.61 we get the following warning:

WARNING: You should add the boolean check kwarg to the run_command call.
         It currently defaults to false,
         but it will default to true in future releases of meson.
         See also: https://github.com/mesonbuild/meson/issues/9300

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14602>

meson.build

@@ -996,7 +996,7 @@ has_mako = run_command(
 from distutils.version import StrictVersion
 import mako
 assert StrictVersion(mako.__version__) > StrictVersion("0.8.0")
-  ''')
+  ''', check: false)
 if has_mako.returncode() != 0
   error('Python (3.x) mako module >= 0.8.0 required to build mesa.')
 endif