meson: only check the libprojectM dependency once

We can check the version value if it's found.

modules/visualization/meson.build

@@ -20,13 +20,9 @@ vlc_modules += {
 }
 
 # projectM visualization plugin
-projectm_dep = dependency('libprojectM', version: '>= 2.0.0', required: false)
-
-if projectm_dep.found()
+projectm_dep = dependency('libprojectM', required: false)
+if projectm_dep.found() and projectm_dep.version().version_compare('>= 2.0.0')
     cdata.set('HAVE_PROJECTM2',1)
-else
-    projectm_dep = dependency('libprojectM', version: '< 2.0.0',
-        required: false)
 endif
 
 vlc_modules += {