auto merge of #11185 : huonw/rust/doc-ignore, r=cmr

Currently any line starting with `#` is filtered from the output,
including line like `#[deriving]`; this patch makes it so lines are only
filtered when followed by a space similar to the current behaviour of
the tutorial/manual tester.

src/librustdoc/test.rs

@@ -173,6 +173,7 @@ impl Collector {
         let libs = self.libs.borrow();
         let libs = (*libs.get()).clone();
         let cratename = self.cratename.to_owned();
+        debug!("Creating test {}: {}", name, test);
         self.tests.push(test::TestDescAndFn {
             desc: test::TestDesc {
                 name: test::DynTestName(name),