Build GCC on CI

Author: Kobzol

src/ci/docker/host-x86_64/dist-x86_64-linux/dist.sh

@@ -14,5 +14,7 @@ python3 ../x.py build --set rust.debug=true opt-dist
 # Use GCC for building GCC components, as it seems to behave badly when built with Clang
 # Only build GCC on full builds, not try builds
 if [ "${DIST_TRY_BUILD:-0}" == "0" ]; then
-    CC=/rustroot/bin/cc CXX=/rustroot/bin/c++ python3 ../x.py dist ci-gcc
+    CC=/rustroot/bin/cc CXX=/rustroot/bin/c++ python3 ../x.py dist \
+      ci-gcc \
+      gcc
 fi