Entry point selection.

$ kotlinc -entry foo.bar.qux ...

selects `qux(args: Array<String>):Unit` in the package `foo.bar` as an entry point.

The short flag is `-e`.

backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2Native.kt

@@ -122,6 +122,7 @@ class K2Native : CLICompiler<K2NativeCompilerArguments>() {
                 put(CommonConfigurationKeys.MODULE_NAME, output)
                 put(ABI_VERSION, 1)
 
+                arguments.mainPackage ?.let{ put(ENTRY, it) }
                 arguments.runtimeFile ?.let{ put(RUNTIME_FILE, it) }
                 arguments.propertyFile ?.let{ put(PROPERTY_FILE, it) }
 

backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2NativeCompilerArguments.kt

@@ -57,6 +57,9 @@ class K2NativeCompilerArguments : CommonCompilerArguments() {
     @field:Argument(value = "-output", shortName = "-o", valueDescription = "<path>", description = "Output file path")
     @JvmField var outputFile: String? = null
 
+    @field:Argument(value = "-entry", shortName = "-e", valueDescription = "<name>", description = "Qualified entry point name")
+    @JvmField var mainPackage: String? = null
+
     @field:Argument(value = "-produce", shortName = "-p", valueDescription = "{program|library|bitcode}", description = "Produce either .kexe, .klib or a .bc file.")
     @JvmField var produce: String? = null