Do x check on various bootstrap tools in CI

Author: Zalathar

src/ci/docker/host-x86_64/pr-check-2/Dockerfile

@@ -28,7 +28,17 @@ RUN sh /scripts/sccache.sh
 
 ENV SCRIPT \
         python3 ../x.py check && \
-        python3 ../x.py check src/tools/bump-stage0 && \
+        # Check some tools that aren't included in `x check` by default, to
+        # ensure that maintainers can still do check builds locally.
+        python3 ../x.py check \
+            bootstrap \
+            bump-stage0 \
+            compiletest \
+            coverage-dump \
+            linkchecker \
+            run-make-support \
+            rustdoc-gui-test \
+            && \
         python3 ../x.py clippy ci --stage 2 && \
         python3 ../x.py test --stage 1 core alloc std test proc_macro && \
         python3 ../x.py test --stage 1 src/tools/compiletest && \