KSyntaxHighlighting: My changes to data files don’t seem to affect test outputs

[Adrian Chaves]

I emptied data/syntax/rest.xml (made it a valid syntax file that would 
mark all text as normal).

Then I run:

     rm -rf build && mkdir build && cd build
     cmake .. && make -j8 && make test

But the contents of build/autotests/html.output/highlight.rst.html are 
still those that would be generated if data/syntax/rest.xml had not been 
changed.