fix: return the compilation exit status

The `cgjavac` script returns systematically 0 (the `echo` exit code). Then, it is never considered as compilation error.

Author: Sylvain Fraïssé

src/main/resources/cgjavac

@@ -3,5 +3,8 @@
 echo "CG> redirect-streams --input err compilation"
 
 java -jar /usr/src/codingame/java-compiler/java-compiler.jar "$@"
+compilationExitCode=$?
 
-echo "CG> redirect-streams --reset --input err compilation"
+echo "CG> redirect-streams --reset --input err compilation"
+
+exit $compilationExitCode