TEST-06-SELINUX: Disable RuntimeBuildSources=

Otherwise fixfiles will try to relabel it which could potentially
lead to disaster. We also change the recommendation in HACKING.md
to set the default so that TEST-06-SELINUX can override it.

docs/HACKING.md

@@ -52,7 +52,7 @@ image all the time when iterating on a patch, add the following to
 
 ```conf
 [Host]
-RuntimeBuildSources=yes
+@RuntimeBuildSources=yes
 ```
 
 After enabling this setting, the source and build directories will be mounted to

test/TEST-06-SELINUX/meson.build

@@ -8,6 +8,9 @@ integration_tests += [
                 # Use 'auto' to automatically fallback on non-uefi architectures.
                 'firmware' : 'auto',
                 'vm' : true,
+                # Make sure we don't mount anything with virtiofs as otherwise fixfiles will try to relabel
+                # it.
+                'mkosi-args' : integration_test_template['mkosi-args'] + ['--runtime-build-sources=no'],
         },
 ]