samples: Minor fixes for bundle

1. Rearrange tasks for C++ and Kotlin compilation in concurrent
sample. It allows the build to download all dependencies before
the compilation.

2. Don't copy *.kt.bc-build directories in the distribution archive.

build.gradle

@@ -397,6 +397,7 @@ task bundle(type: Tar) {
         exclude '**/settings.gradle'
         exclude '**/build'
         exclude '**/.gradle'
+        exclude 'samples/**/*.kt.bc-build'
         rename('(.*)\\.for_bundle', '$1')
         into baseName
     }

samples/concurrent/build.gradle

@@ -14,10 +14,11 @@ konanArtifacts {
 }
 
 task compileCpp(type: Exec) {
+    dependsOn 'genMessageChannelInteropStubs'
     workingDir project.getProjectDir()
     commandLine './buildCpp.sh'
 }
 
-genMessageChannelInteropStubs {
-    dependsOn(compileCpp)
+compileKonanMessageChannel {
+    dependsOn 'compileCpp'
 }