DO NOT MERGE ANYWHERE - Update tools_ndk_r9d to use main branch.

Bug: b/289400079
Change-Id: I54d425a9310462a56a3a2d8a5b9032e906c7956d
diff --git a/default.xml b/default.xml
index ba931e8..21ead69 100644
--- a/default.xml
+++ b/default.xml
@@ -4,7 +4,7 @@
   <remote  name="aosp"
            fetch=".."
            review="https://android-review.googlesource.com/" />
-  <default revision="master"
+  <default revision="main"
            remote="aosp"
            sync-j="4" />