Do not build GCC in fast try builds

Author: Kobzol

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

@@ -10,4 +10,7 @@ python3 ../x.py build --set rust.debug=true opt-dist
     build-manifest bootstrap
 
 # Use GCC for building GCC, as it seems to behave badly when built with Clang
-CC=/rustroot/bin/cc CXX=/rustroot/bin/c++ python3 ../x.py dist gcc
+# 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 gcc
+fi