Fix CLI test data on -XXLanguage arguments

We should use '\:' instead of ':' because the latter is replaced to the
path separator in AbstractCliTest.readArg which is ';' on Windows.

compiler/testData/cli/jvm/internalArgNoWarningForEnablingBugfix.args

@@ -3,4 +3,4 @@ $TESTDATA_DIR$/simple.kt
 $TEMP_DIR$
 -language-version
 1.2
--XXLanguage:+ProhibitDataClassesOverridingCopy
+-XXLanguage\:+ProhibitDataClassesOverridingCopy