It seems JDK-8251121 has introduced the jtreg dependency that breaks the CTW builds.

$ export JAVA_HOME=<point to build>
$ export PATH=$JAVA_HOME/bin:$PATH
$ cd test/hotspot/jtreg/testlibrary/ctw
$ make

echo '${JAVA_HOME}/bin/java ${JAVA_OPTIONS} --add-exports java.base/jdk.internal.jimage=ALL-UNNAMED --add-exports java.base/jdk.internal.misc=ALL-UNNAMED --add-exports java.base/jdk.internal.reflect=ALL-UNNAMED --add-exports java.base/jdk.internal.access=ALL-UNNAMED -XX:-UseCounterDecay -Xbatch "-XX:CompileCommand=exclude,java/lang/invoke/MethodHandle.*" -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:wb.jar -jar ctw.jar $@' > dist/ctw.sh
chmod a+x dist/ctw.sh
/home/shade/trunks/jdk-jdk/build/linux-x86_64-server-fastdebug/images/jdk//bin/../bin/javac -sourcepath ../../../../../test/lib \
-d build/classes \
-cp build/classes \
@wb_filelist
/home/shade/trunks/jdk-jdk/build/linux-x86_64-server-fastdebug/images/jdk//bin/../bin/jar --create --file=dist/wb.jar -C build/classes .
/home/shade/trunks/jdk-jdk/build/linux-x86_64-server-fastdebug/images/jdk//bin/../bin/javac --add-exports java.base/jdk.internal.jimage=ALL-UNNAMED --add-exports java.base/jdk.internal.misc=ALL-UNNAMED --add-exports java.base/jdk.internal.reflect=ALL-UNNAMED --add-exports java.base/jdk.internal.access=ALL-UNNAMED -sourcepath src -d build/classes -cp dist/wb.jar @filelist
../../../../../test/lib/jdk/test/lib/util/CoreUtils.java:31: error: package jtreg does not exist
import jtreg.SkippedException;
            ^
../../../../../test/lib/jdk/test/lib/util/CoreUtils.java:136: error: cannot find symbol
                throw new SkippedException("Directory \"" + coresDir + "\" is not writable");
                          ^