Disable NewInference for stdlib tests

There is one failing test namely `ValByMapExtensionsTest.doTest`, which
 is quite questionable because its checks the use of out projection and
 Exact annotation (see KT-18789)

libraries/stdlib/samples/build.gradle

@@ -15,7 +15,8 @@ compileTestKotlin {
         freeCompilerArgs = [
                 "-Xuse-experimental=kotlin.ExperimentalStdlibApi",
                 "-Xuse-experimental=kotlin.ExperimentalUnsignedTypes",
-                "-Xuse-experimental=kotlin.time.ExperimentalTime"
+                "-Xuse-experimental=kotlin.time.ExperimentalTime",
+                "-XXLanguage:-NewInference"
         ]
     }
 }