Add a parent icing project to settings.gradle

Adding foo:bar project with a custom directory, causes Gradle
to assume that foo is in frameworks/support/foo. There is no such
project thus the parent project needs to be explicitly specified. This
fixes Android Studio warning:
Warning:<i><b>root project 'androidx': Unable to resolve additional project configuration.</b>
Details: org.apache.tools.ant.BuildException: Basedir /ssd/ssd2/androidx-master-dev/frameworks/support/icing does not exist</i>

Test: Gradle sync in studio no longer shows this warning
Change-Id: I5fbbf3acd249de33e3c323a1b57e9e47ce255a4b

diff --git a/settings.gradle b/settings.gradle
index 83eef67..afd3a465 100644
--- a/settings.gradle
+++ b/settings.gradle

@@ -408,6 +408,7 @@
 apply(from: "include-composite-deps.gradle")
 File externalRoot = new File(rootDir, "../../external")
 
+includeProject(":icing", new File(externalRoot, "icing"))
 includeProject(":icing:java", new File(externalRoot, "icing/java"))
 includeProject(":icing:nativeLib", new File(externalRoot, "icing/nativeLib"))
 includeProject(":noto-emoji-compat", new File(externalRoot, "noto-fonts/emoji-compat"))