tests: Always separate rendercheck -f and -o options with a space

4 jobs for fix-rendercheck-options in 7 minutes and 11 seconds
Status Job ID Name Coverage
  Docker Image
passed #208912
debian-testing

00:01:08

 
  Build And Test
passed #208913
autotools-build-and-test

00:06:03

passed #208914
meson-build-and-test

00:01:45

 
  External
passed continuous-integration/appveyor/branch