Never use JVM IR to compile coroutines-experimental

JVM IR backend doesn't support old coroutines, so we disable it via
-Xno-use-ir, just as for the main source set. This option has no effect
for the current master builds, but will be necessary once JVM IR is
enabled project-wide.

libraries/stdlib/coroutines-experimental/build.gradle.kts

@@ -60,14 +60,19 @@ tasks {
         kotlinOptions {
             languageVersion = "1.2"
             apiVersion = "1.2"
-            freeCompilerArgs = listOf("-Xcoroutines=enable")
+            freeCompilerArgs = listOf(
+                "-Xcoroutines=enable",
+                "-Xno-use-ir"
+            )
         }
     }
     val compileMigrationTestKotlin by existing(KotlinCompile::class) {
         kotlinOptions {
             languageVersion = "1.3"
             apiVersion = "1.3"
-            freeCompilerArgs = listOf()
+            freeCompilerArgs = listOf(
+                "-Xno-use-ir"
+            )
         }
     }