doc: disable gtk-doc test again - you are a really annoying piece of software

make  check-TESTS
make[5]: Nothing to be done for `/usr/bin/gtkdoc-check.log'.
fatal: making test-suite.log: failed to create /usr/bin/gtkdoc-check.trs
fatal: making test-suite.log: failed to create /usr/bin/gtkdoc-check.log
make[4]: *** [test-suite.log] Error 1
make[3]: *** [check-TESTS] Error 2
make[2]: *** [check-am] Error 2
make[1]: *** [check-recursive] Error 1
make: *** [check] Error 2