Unmark source roots in 'builtins' and 'runtime.jvm'

This is needed because until we have modules and dependencies implemented in
our IDEA plugin, the whole project always is analyzed to highlight any file in
the project. This resulted in weird errors in different modules in Kotlin
project because two declarations were found for each built-in class: the one in
kotlin-runtime.jar and the one (totally unrelated) in the 'builtins' module

core/builtins/builtins.iml

@@ -2,9 +2,7 @@
 <module type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-    </content>
+    <content url="file://$MODULE_DIR$" />
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>

core/runtime.jvm/runtime.jvm.iml

@@ -2,9 +2,7 @@
 <module type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-    </content>
+    <content url="file://$MODULE_DIR$" />
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
     <orderEntry type="module" module-name="builtins" />